Answer : D. Few people think seriously of doing something about accidents.
The sentence is said to be in an active voice when the subject of the sentence is the doer of the action therefore, the sentence in letter D is in the active voice. The subject of the sentence in letter D is "few people" while the verb is "think", the few people do the thinking meaning the subject is the doer. The other options above showed what is contrary to active voice that is the passive voice.
If they were competing for a marching band, many members would be able to join. Also, they wouldn't be competing for a "chair." Same for symphony orchestra. Hope this helps! :)
Answer: It means that people show their true colors when there by theirself and they arnt typically fake around other people but only they know their true selves its just like the expression "What you do in the dark always comes to light"
