Answer:
Terror is the correct answer.
Explanation:
Frankenstein or the Modern Prometheus is a novel written by Mary Shelley. Through letters, aspects related to ethics in science and life in general are discussed in the novel.
In this excerpt, we can see through semantics how terror is transmitted by the emotions described there. We can see how the narrator describes the pulse that beat "so quickly and hardly", being so intense that the speaker "felt the palpitation of every artery." Even the narrator mentions dreams, the passage uses them to indicate loneliness, meaning that the speaker feels so lonely that not even his dreams are with him anymore.