The store was robbed just after midnight.

A) This sentence is active already.

B) This sentence can be rewritten in active voice.

C) This sentence cannot be rewritten in active voice.

The answer is explained below.

Explanation:

Option A is incorrect because the sentence is passive: the subject, the store, doesn't perform the action but receives it.

Option B is correct because the sentence could be expressed as Somebody robbed the store just after midnight. By using an indefinite pronoun, we express that we don't know who did it.

Option C is incorrect because as seen in the previous explanation, this sentence can be expressed in active voice.

this sentence is active already