"You are a girl."
Translation:Tu sei una ragazza.
In English, "to be" has a dual meaning in latin languages ie: Spanish, Portuguese and Italian, to be can be used with dual verbs: yo soy/yo estoy; eu sou/eu estou; so I think in Italian should be differentiated as well, thus the proper translation of this word (verb conjugated as sei) should also be similar to the word è used on answer 3 of this question. Am I right? I can understand that for the purpouses of the lesson, sei could be a better answer, so your indications: "Mark all that applies", should allow for answer 2 and 3.