Answer: The right answer is stanza 4.
Explanation: In the first three stanzas the speaker is describing and comparing the two diverging roads. One "bent in the undergrowth," so it was, perhaps, more unknown, yet more alluring. The other one had "the better claim," "because it was grassy and wanted wear." Even though that morning none of them had been traveled, he opted for the first one. In the last stanza he reflects upon his choice: "I took the one less traveled by / And that has made all the difference." This can be interpreted as a regret, perhaps because the road has turned out to be very bumpy, metaphorically speaking, although eventually something good has come out of it.
