Final answer:
Excerpts from the text suggest that characters like Lassiter are aware of hidden dangers and act with caution, which can parallel Rosie’s understanding of strange events in the forest. The metaphorical reference to 'shadows on the sage-slope' encroaching around Jane's life also reflects the likelihood of Rosie possessing more knowledge about the threats than she has let on.
Step-by-step explanation:
To support the inference that Rosie knows more than she is letting on about the strange occurrences the Lumberjane Scouts experienced in the woods, we can draw upon specific excerpts from the provided texts. For example, the passage describing how Lassiter warns Jane Withersteen of being watched and the need to talk low indicates a knowledge of espionage and hidden dangers. Moreover, Lassiter's careful approach to revealing information and his significant preoccupation after his trip suggests that he, and possibly Rosie by association, are withholding full transparency about the hazards they are aware of. Additionally, the reference to the shadows on the sage-slope as a metaphor for the encroaching danger around Jane's life mirrors the potential knowledge Rosie possesses regarding the looming threats that she has not fully disclosed. These examples demonstrate a pattern of characters in the story recognizing more than what they openly acknowledge, allowing us to infer that Rosie, too, is likely more knowledgeable about the eerie events than she reveals.