The answer is all of these.
The Duke is the speaker of the poem where he is entertaining an emissary who has come to negotiate the Duke's marriage. As he shows the visitor through his palace, they came across the portrait of the late Duchess. The Duke then began to reminisce about the portrait sessions and then about the Duchess herself. As his monologue continues, the reader realizes that it was the Duke who caused the untimely demise of the previous Duchess.
A denouement is the final part of a play, movie, or narrative in which the strands of the plot are drawn together and matters are explained or resolved.
And based off the answers...
A. By returning to the original location, Bierce ends the story by contrasting Druse's actions to the beginning of the story.
B. The description of the Federal sergeant crawling to Druse allows Bierce to show how the soldiers must remain hidden.
C. Describing Druse's location and feelings allows Bierce to enhance how monstrous Druse feels at the end of the story.
D. Through the setting, Bierce is able to explain the climax and resolve Druse's feelings about killing his father.
I believe that the correct answer is D.
Well you can’t live without food and water because water hydrates you and well food keeps you not from starving cause it could possibly kill you I’m pretty sure so yea