Answer:
Alejandra iba al cine.
Explanation:
The singular form of the verb "ir" is "iba". The subject of this sentence (Alejandra) is singular, so "iba" is the only option that can be correct. The words "ibamos" and "Iban" are plural. And "ibas" is only used with the subject "Tu". In this case, the subject is "Alejandra" = "Ella" (she) can only be combined with the verb "iba".
