"Ellos no lo tuvieron."
Translation:They did not have it.
I disagree with Duplingo's translation. 'They didn't have it' would translate 'No lo tenían' whereas 'No lo tuvieron' ought to be translated 'They didn't get it', cf. "The preterite tense is used to refer to actions that occurred at a fixed point in time." (http://www.studyspanish.com/verbs/lessons/pretreg.htm) whereas "The imperfect tense is used to refer to actions in the past that occurred repeatedly." (http://www.studyspanish.com/verbs/lessons/impreg.htm). In this way tener means have in the imperfect and get in the preterite, just as conocer means know in the imperfect and to get to know in the preterite ... at least to the best of my knowledge.
You can't switch verbs from 'to have' to 'to get'. They are obviously usually related concepts in everyday life, but they are different verbs.
The problem you are having is that English and Spanish do not always make the same distinctions. In English, the past participle, preterite, or a “used to + (present tense verb)" are used to indicate past imperfect (depends on the verb and the situation).
English doesn't have a dedicated past imperfect tense that is used on all (most) verbs in all (most) situations like Spanish has. Both of those Spanish sentences would be phrased the same in English.
"tu" is not there. There are many of this type of questions that have the wrong word as the answer.
When you've gotten it wrong enough times, you will no longer need it to be there.
Yes, is the simple past of "tener" just with the noun "ellos", "Ellas" o "USTEDES."