- Miguel, ¿qué piensas hacer esta noche?
___ ir a la fiesta.
O A. Vamos
B. Pienso
C. Voy
D. Pensamos

pienso

Explanation:

if theres an “ a “ before the “ ir “ it would be “ voy a ir a la fiesta “ but since there is none and theyre asking what hes thinking about doing then he will answer “ pienso ir a la fiesta “ because it translates to “ I think im going to the party “.