Why does Poe use the refrain nevermore in "The Raven"?

Read the quotation from "an occurrence at owl creek bridge." and now he became conscious of a new disturbance. striking through the thought of his dear ones was a sound which he could neither ignore nor understand, a sharp, distinct, metallic percussion like the stroke of a blacksmith’s hammer upon the anvil; it had the same ringing quality. he wondered what it was, and whether immeasurably distant or near by—it seemed both. its recurrence was regular, but as slow as the tolling of a death knell. he awaited each stroke with impatience and—he knew not why—apprehension. the intervals of silence grew progressively longer, the delays became maddening. with their greater infrequency the sounds increased in strength and sharpness. they hurt his ear like the thrust of a knife; he feared he would shriek. what he heard was the ticking of his watch. which best describes the effect of the narration in the excerpt? it suggests that the man being executed feels tranquil and at peace. it suggests that the narrator is sympathetic to the man being executed. it suggests that the plot will become less tense as the story continues. it suggests that the story will become more intense and mysterious.