Answer:
Using an unreliable and excitable narrator allows Poe to explore irrationality and strong emotions.
Step-by-step explanation:
The protagonist of The Tell-Tale Heart is a lunatic, a crazy man who is irritated by the old man in whose house he lives in to the point where he decides to kill him. During the story, we see the protagonist's erratic thoughts, maniacal ideas, and ultimately, his impromptu decision to murder the old man because of his 'devil eye.'
The narrator is unreliable, meaning that we cannot trust him because of his jumbled thoughts and powerful emotions.