Final answer:
The narrator or an omniscient observer notes the crossing of the Great Salt Lake while the girl is asleep. 'The sound of the lake was inside her' indicates a profound subconscious connection between the girl and the lake.
Step-by-step explanation:
The student's question centers around a passage from a narrative and asks who observes the crossing of the Great Salt Lake while the girl is asleep. As the girl is asleep, it is the narrator or possibly an omniscient observer in the story who is noting the event.
When the narrator says, "the sound of the lake was inside her," it suggests a deep connection or resonation that the lake's presence or memory has with the girl, even in her sleep. This can imply that the environment has a profound impact on her subconscious or that the lake holds a significant meaning or memory for her, thereby echoing within her even when she is not physically awake or aware.