In comparison with active voice, passive voice:

A) reveals the doer of an action.
B) subordinates an unpleasant thought.
C) reinforces finger-pointing.
D) conveys ideas more vividly.

Passive voice is often used to avoid stating who is responsible for an action, which can be helpful in certain situations where pointing blame is not productive. However, it can also make writing less clear and direct. Therefore, B is the correct answer, as it mentions the subordination of an unpleasant thought.