Answer:
A. narrator reveals that he committed the murder
Explanation:
In "The Tell-Tale Heart", the narrator is shown to have created the perfect plan; everything went his way and if he hadn't said anything, the police would have never found the body.
Thus, one would expect the narrator to have gotten away with the murder.
However, though options B and C both were expected by the reader (he had explained previously that this was what he had planned on doing), the narrator openly revealing that he had committed the murder would come as a surprise.
So, the answer is A.
