Question

Yo _______________ en el coro.

Answer 1

Yo _________ en el coro.

Translation:
I [blank] in the choir. (Coro also means "chorus", but clearly "choir" is the definition being used here.)

One sings in a choir. The infinitive for "to sing" in Spanish is cantar; this must be conjugated for our verb. The verb is yo, which is first-person singular. The conjugation is canto.

Answer:
canto

Yo canto en el coro.

Answer 2

Yo canto en el coro.