Final answer:
The narrator wants to kill the old man because of his unsettling eye.
Step-by-step explanation:
The narrator in "The Tell-Tale Heart" wants to kill the old man because of the old man's eye. The narrator describes the eye as resembling that of a vulture, with a pale blue color and a film over it. The sight of the eye makes the narrator's blood run cold, and he decides to take the life of the old man in order to rid himself of the eye forever.
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