In the given excerpt from "Shout: A Poetry Memoir," the detail that best contributes to an uncertain mood is "whiskers quivering, eyes wide."
1. "Whiskers quivering, eyes wide" conveys a sense of fear, nervousness, or anxiety. This description of the speaker's reaction to the move from the countryside to the city suggests a feeling of uncertainty and unease.
2. The image of "whiskers quivering" typically relates to a small animal being on edge or feeling vulnerable, which can symbolize the speaker's apprehension about the new environment and situation.
3. The phrase "eyes wide" further emphasizes a heightened state of alertness or surprise, hinting at the unknown and possibly overwhelming experiences that the speaker is encountering during the transition.
4. Together, these details paint a picture of the speaker's emotional state, contributing significantly to the uncertain mood of the excerpt as they navigate a major change in their life.
Therefore, the detail "whiskers quivering, eyes wide" best contributes to an uncertain mood in the excerpt by highlighting the speaker's sense of trepidation and the unfamiliarity of the situation.