According to me C is written in passive voice
To be completely honest with you I really don’t know
He could not find a hint; He could not find a sign; He could not find a trail; He could not find a clue.
A) He wants to undermine Snowball's credibility by mentioning him.
B) He wants to suppress a potential uprising of the animals.
C) He wants to distract the animals from learning the truth.