Final answer:
The speaker reacts poorly to the raven's response of "nevermore" in stanzas 15-16 of "The Raven" because it represents a bleak and hopeless future.
Step-by-step explanation:
In stanzas 15-16 of "The Raven," the speaker reacts poorly to the raven's response of "nevermore" because it symbolizes a bleak and hopeless future. The repetition of this word reinforces the speaker's despair and emphasizes the finality of the raven's answer. The speaker becomes increasingly agitated and frustrated, as he realizes that he will never be able to escape his grief and loneliness.