This question is about "the tale tail heart"
Answer and Explanation:
The narrator is not a reliable narrator because he narrates the facts in first person, that way we only know what happens from his point of view, we have no other point of view to compare and have a panoramic view of all the facts, that is, our conclusions are manipulated by the narrator, he can lie and we will never know.
Furthermore, the narrator seems to be an unreliable person, since he has negative thoughts about the old man, who does not distrust him. This means that he behaves positively in the presence of the old man, but reveals a maleficent nature when he is alone with his thoughts.