Final answer:
The author characterizes Lois' sentiment by comparing the fading memory of the shout to a footprint obscured by other footprints, capturing the eroding nature of her once clear memory. option b is correct.
Step-by-step explanation:
The author characterizes the sentiment Lois experiences regarding the shout she heard on the cliff in a specific way. Among the options provided, B) The author figuratively compares this phenomenon to a footprint that has been trampled over by more footprints is the mention correct option. This characterization suggests interference with the character's memory, akin to the way overlapping footprints can obscure the details of the original impression.
While the other options may seem viable, the given textual evidence does not support foreshadowing, multiple rationales, or distraction due to preoccupation as the primary characterization in this context. The essence of the sentiment, as characterized by the author, is the erosion of a once clear memory, much like the way multiple footprints can distort the clarity of the first mark left upon the ground.