1. I would say the correct answer is A) He uses an extended metaphor to convey the magnitude of his sorrow about having to surrender. Sun is the extended metaphor here; it depicts their faltering hope and future that doesn't exist. True, there is a simile in the passage, but it doesn't mark the passage semantically and stylistically as this metaphor does.
2. In my opinion, the correct answer is C) It conveys finality and hopelessness about the future. As I said, the sun here is a metaphor for their happiness and prosperity. That was the last time Black Hawk was able to actually see the sun, and he will never be able to do it again, as his people are definitely defeated and cast off their lands.
