Answer: The statement that best describes how the structure of the poem contributes to its meaning is "The rhymes in the paired lines emphasize each speaker's view about resting or moving forward." The rhyme scheme and the repetition of the phrase "Stop a while" in Maiden's lines, as well as the repeated phrase "Onward still" in River's lines, create a contrast between the two speakers' viewpoints on resting or moving forward. The structure of the poem emphasizes the tension and opposition between the two speakers, and their different perspectives on the nature of time, movement, and rest.