An act of speaking one's thoughts aloud when by oneself or regardless of any hearers, especially by a character in a play:

Answer: Option B

The one word substitution is Soliloquy.

Sinecure : a position requiring little or no work but giving the holder status or financial benefit.
Pessimist : a tendency to see the worst aspect of things or believe that the worst will happen.
Philanthropist : a person who seeks to promote the welfare of others, especially by the generous donation of money to good causes.
Soliloquy : an act of speaking one's thoughts aloud when by oneself or regardless of any hearers, especially by a character in a play.