The answer is A. The mood in any piece of literature is determined by feeling created. You can think of this by using context clues. Think of your mood right now, perhaps you're relaxed. Mood is a type of internal feeling felt by a human being, and mood is generally used in writing to evoke emotion, or reasoning!! Hope this helped.
C. it underscores the narrators obsession.
I can't really for certain but it's either B.) "It introduces the Conflict that is the poem's focus" or C.) "It uses repetition to show there were six hundred men" A is wrong because it shows no evidence of a flash back. and D is wrong because it wasn't said that they will triumph.
