Answer: In lines 16-20, the rhyme scheme abaab is used. The mood expressed through the words is that of wistfulness and reminiscence.
Sentimentality is also known to be manipulative. Oftentimes, sentimentalism obscures the facts of an actual event. Indeed, in this stanza, the narrator changes what he said earlier in the poem (that the two paths "had worn... really about the same") and states "I took the one less traveled by, / And that has made all the difference." This is a sentimental trick. He views his actions as having made all the difference, but he actually chose the path almost at random. These sounds ("I") add to this wistful, sentimental shift.
