Answer:
C
Step-by-step explanation:
He is saying that there are 2 roads leading away from a critical point in everyone's life.
He is glad that he has chosen the one that is less travelled which means he has gotten what he could from the life he lived.
Jesus says much the same thing in Matthew 7:13 and 14. One way leads to destruction, the other is the righteous path.
I think Frost had this in mind when he said that the less travelled path has made all the difference to him, because he is not lead by other people.
I think given what I have written, I believe that C is the correct answer. I don't think the metaphor means anything to do with nature. It has to do with moral behavior.