Answer:
C. irony
Step-by-step explanation:
A. is not the correct answer. Symbolism is representing one idea through artistic imagery with symbols and metaphors.
B. is not the right answer. The allusion is indirectly explaining something, not explicitly going into the details of it, but making an artistic connection.
C. is the right answer. Irony presents us the two radically different ideas. It is most often used as a humorous device. We can read that this case is the irony as the narrator first declines to tell his autobiography, but then actually does so despite his promises and words. We see these two ideas as contrasting – despite the first promise, we still get the story of the narrator at the end.
D. is not the right answer. A metaphor is a figure of the screen through which the writer refers to one thing through the other, by similarities of the ideas.