The answer is: C. The line lengths vary, which suggests the chipmunk's movement: quickly running, then stopping and watching for danger.
When you read this stanza you can infer that the sunset reflect the color of the chipmunk fur, that when you imagine the chipmunk going to rest the picture shows her sluggish and unmotivated, because at sunset she hides from the danger, however none of this description shows the movement of the chipmunk, she actually start the stanza “Curled at his breast”.