Final answer:
The key detail to include in a summary from the passage is the family's visit to the O.K. Corral, as it is significant to the narrative's historical setting and the characters' experiences.
Step-by-step explanation:
When summarizing a passage, the key detail that should be included is the one that conveys the main events or themes of the text.
In the provided passages, many details revolve around personal emotions and the environment, but one consistent theme is the journey and decisions of the characters, their emotional transformation, and their relationship with the environment.
For instance, the family's visit to the O.K. Corral stands out as a significant event that embodies the historical setting and personal experiences of the characters, which are central to the narrative.
While Allie's excitement, her father's interests, and her disappointment are more personal and nuanced details, the visit to the O.K. Corral holds symbolic value and ties into the larger context of the story's setting in the West.