Which statement is written in passive voice?
a. the firefighters fought bravely against the wildfires in the forest.
b. the acrobats at the circus brought joy to the children in the crowd.
c. the town hall was filled by the concerned citizens of the area.
d. the teacher inspired her students to be the best they could be.

The easiest way to identify passively voice is by checking out your verbs. choice A has "fought," choice B has "brought," choice C has "was filled," and choice D has "inspired." choices A, B, and D are all in active voice--the verb moves the action forward, and the subjects perform the listed verbs. the firefighters fight, the acrobats bring joy, the teacher inspires. choice C, however, has "was filled." rather than saying "the concerned citizens filled the town hall" (active voice, where the verb directly applies to the citizens and states the action the citizens are performing), it gives you a roundabout sentence. "the town hall was filled" instead gives the verb, which SHOULD apply to the citzens, to the town hall. C is the choice which uses passive voice.

C is correct it is the only sentence with the past tense verb

Abecause you are smart at every thing