Now I see what you're asking. The 1st person conjugation is different (that was answered already, so I assume you're okay with that part of your question). You cannot tell whether it's he, she or it from the sentence as provided. That's actually not important in real live conversations. As someone else noted, it will have been made clear by the time this sentence comes up. If not and you want to know, you just have to ask the speaker.
But maybe your real question is about what to plug into Duo. When there are 2+ possibilities, try different variations and see how Duo reacts. If it rejects something, come to the comments to see if you were actually correct or if there's some reason for the rejection. Sometimes, there will be a clue in some other word, such as an adjective that agrees in gender and number. Other times Duo will reject for no good reason (for example, it seems to like tú forms much more than usted). You can always compare to a verb conjugator or get help from other users.
In the end, if you feel Duo was wrong to mark an answer as incorrect, flag your response. Duo is still adjusting its grading for many of these sentences.
Also, the choices for the conjugation are "he, she or it," (and, I think, the plural "you" - I am open to correction) and Duo's translation for me when I spoke the sentence was "He received wine." That can easily be understood as when someone receives communion, yes?
Obtener (just like tener) is part of a group of verbs with irregular stems in the preterit. There are stems with "i" like hacer (hic-) & querer (quis-), stems with "u" like estar (estuv-) & poner (pus-), and stems with "j" like conducir (conduj-) & decir (dij-).
All of these verbs use the same irregular endings: -e, -iste, -o, -imos, -isteis, -(i)eron and none of them have accents.
The cause for confusion is that the English verb "get" means both "to be given something by someone" and "to get something by yourself."
In Spanish, "obtenir" means "to obtain/to get" and "recibir" means "to receive/to get." (His friends obtained/got him his tickets for the show/Sus amigos lo obtuvieron a él las boletas por el espectáculo) and "recibir" means to "receive" (Él recibió una pensión del Estado/He received/got a pension from the State).
"Obtuvo" is from "obtener" which means "to obtain, to secure, to get" and "recibió" is from "recibir", which means "to receive, to get". So it looks like they have "to get" in common but "obtain" and "receive" have different meanings in English. Think of how they might be used in a football game. If you receive the ball, someone passes (gives) it to you, but if you obtain the ball, you probably took it from someone else or got it when it was loose. "Obtain" means to succeed in gaining possession of by planning or effort , but "receive" has the connotation of taking or acquiring something given. I'm assuming the Spanish has those shades of meaning as well, but that could be wrong. And whether you took it or it was given to you, you still got it; so you get it either way.
The literal Spanish "Obtuvo vino/It got wine" might be best translated to English in the passive, as in Se obtuvo vino/Wine was obtained." I suspect that just as "It got wine" is jarring to the ears of English speakers, "Se obtuvo vino" is equally jarring to Spanish speakers because it's not necessary to use the "se" (it being redundant) in Spanish. I'd love to hear from a native Spanish speaker if I'm correct about this.
It is, but it's that and so much more. Really, the Spanish verb obtener is not limited to obtain. What Duo is doing here is teaching you it can mean "receive." If you don't get caught up with the English cognate, you'll see that obtener is actually a different word from obtain.
How it sounds (to us English speakers) is very dependent on the letters surrounding the v/b. In this case, even though the "o" preceding the "v" is in the previous word, when the sentence is said at a natural speed it sounds like and/or transitions into a "v" sound more naturally than a "b" one, when using the Spanish way of forming the sound. This is generally true of vowel sounds and some consonant sounds, whereas after other consonants (or silence) it tends to sound more like a "b" to our ears. It also depends on what sound follows the v/b. In reality there are no hard rules, it just comes down to what comes naturally in flowing Spanish speech.
Watch this video from 5:30 onwards for an example of what I'm talking about: https://youtu.be/x9t3C0VSoq0?t=5m30s
To elaborate, native Spanish speakers don't see the difference, they understand it as the same sound, due to it being formed the same way with the mouth. This is somewhat different to the way we form the English v and b sounds. You can make it by trying an English "b" sound but softer, with the lips only lightly touching. Part of the reason for the differences to an English ear that I mentioned in the first paragraph is the difference in strength at which the lips naturally touch in different contexts.
This has basically been answered above by elanaknt (near the top) and yourself. But if you put the pieces together: The accent is added to distinguish between the present tense first person and the preterite third person where they would otherwise be the same. In this case the two words are very different: obtengo (I obtain) and obtuvo (he/she/it obtained). i.e. Because the stem changes in the preterite, the difference is 'obvious' therefore the accent is not needed! Hope that helps. :-)
He received wine is one possible answer to this question, and probably the default without further information. Duo wil usually allow he, she or usted in response to this type of question because any of them could be correct and in the English answer they are very necessary. But please note that most Spanish speakers do not use the subject pronouns (yo, tú, el, ella ... ) very much as they are implied by the conjugation of the verbs. They would ony put them in if they were really needed for clarification or for emphasis.
It's not the sentence you were asked to translate, but the answer is "yes," "He RECEIVED wine" is the translation of "Él recibió vino." I capitalized the word "received" so that you could see the correct spelling. The old grammar school rule rule: "I" before "E" except before "C," excepting "weirdo," which is weird. ;^)
I believe that the duo program is trying to reinforce that third person singular CAN mean "she" instead of "he." Of course, this is in context, where you know that the person who is doing the action is female. It's the only way that I can see for the program to introduce the idea that YOU DON'T NEED the pronoun subject because it is already understood to be there. In fact, there is a term for using the first person singular too much. The term is "yo-ismo." I don't know whether or not the term also means unnecessary use of the third person pronouns when they are unnecessary.
Shuldn't there be an accent on the last o of obtuvo if the verb is meant to be in past tense third person, and not in yo form? Or is obtuvo an irregular? I originally translated the phrase to "I get wine" because there was no accent on the o. Why is that incorrect, and how is this sentence in the past tense?
https://www.aboutespanol.com/los-verbos-irregulares-en-espanol-2879644 ObtenER yo obtuve tú obtuviste él, ella, Ud. obtuvo nosotros obtuvimos vosotros obtuvisteis ellos, ellas, Uds. obtuvieron vos obtuviste https://www.buscapalabra.com/como-se-escribe.html?palabra=obt%C3%BAvo
Typically -ó is the ending to preterite -ar verbs and -ió is the ending for preterite -er and -ir verbs, but in this case, the verb obtener is irregular in the same way as tener. The root for this particular irregular verb is obtuv. In the preterite, -o is the ending for all irregular verbs in the ud. form. Therefore, obtuvo would be the irregular pretitite ud. form. It is only in the present tense that the ending -o is used for the yo form. In this case, obtener would also be congugated like the irregular verb tener, and be obtengo, not obtuvo. Almost all irregular preterite verbs use the following endings: -e, -iste, -o, -imos, -isteis, -(i)eron and none of them have accents.
Apropos the discussion of translating obtener, spanishdict.com is a great resource for checking out multiple meanings in English of Spanish words with lots of examples. Sometimes there is a direct one to one literal translation e.g. 'gato' 'cat'. More often the Spanish word has multiple meanings in English. It is impossible without context as in Duolingo exercises, to know which English meaning is intended. As another poster pointed out, Duolingo tries to show multiple meanings by allowing different 'correct' answers.