The answer is A. prepositional phrase
The answer is B. "He asked himself where it had come from and how; the past provided no explanation, and the future could not justify it."
This option is not a dark humor because it does not show the opposite side of happiness. The other choices explain that although there is happiness, he considered it as a burden- making it a dark humor.
The answer is compound. It has more then one subject happening in the situation.
