Poetry tells a story and expresses emotion in a way that is concise, emotionally charged, and musical. There are different types like a narrative and lyric. A narative tells a story, which has a plot and characters. A lyric poem is more about feelings and emotions. The speaker is the character.
D would be the only example of a character study. None of the other options examine a specific character and D goes into depth researching Harry Potter as a character. I hope this helps!