Explanation: A frame story is a narrative that is presented as a way to contain a second, more developed story (or series of stories). In this case, O'Brien receives a question from his daughter, Kathleen. She asks him whether he ever killed anyone. This story leads us to a second story, in which O'Brien reflects on his past and his role in the war. The use of a frame story structure enhances the theme that the past can leave a strong imprint on the present.
The correct answer is B, the character Kiowa. The story narrated in first person talks about a war from the past and it is the death of Kiowa that leaves a long lasting impression on the narrator. This is because he, a person, now only became a statistic of the gruesomeness of war, as does everyone else who participates in a war eventually.
