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"
Explanation:
I believe the answer is going to be A but without the underlined phrase I am not 100% sure.
I think a. use of verb tenses
"think"
Put a semicolon because it is 2 independent clauses