I chose "nemen" out of the three options; neem, neemt and nemen. I know neemt is right also but doesn't "nemen" work in this case too? If no why not?
Yes, but it was impossible for me to know what the English translation would be, it could be either.
Clarification; the exercise was a dutch sentence (no translation visible) with a missing word and I had to pick which one was correct. "Zij _ _ _ de schoenen". I'm guessing it's an error, show "neem" instead of nemen and neemt together as they would both be correct...
Just look at the verb. Neem(t) is always singular, nemen is always plural (or infinitive or gerund/progressive). As both zij=she and zij=they are third person, that's the only thing that matters and fortunately even in English the third person verb forms still distinguish singular ([he/she/it] takes) and plural ([they] take).
- Zij neemt de schoenen. = [She/They] takes the shoes.
- Zij nemen de schoenen. = [She/They] take the shoes.
You can see which it is without even looking at the Dutch sentence.
Or to put it differently: If someone came up with a new English personal pronoun zee that can meen either she or they, there would be no cause for confusion:
- Zee takes the shoes. = She takes the shoes.
- Zee take the shoes. = They take the shoes.
Click on the "Report a Problem" tab which is to the left of "Discuss Sentence" in the lesson page. Or press the Support tab to the left now, but then you must provide all the information about which lesson and exactly what happened. Next time you go through the lesson, take a screen shot of it and post that to Report a Problem. Here is a Discussion (found in Popular section of Discussion tab at top of page) about the discussion page which has a screen shot of a lesson page to show you where Discuss Sentence is and you can see where the Report a Problem is: https://www.duolingo.com/comment/3732786