Which one represents interesting symmetry in Sir Gawain and the Green Knight: the number of presents to the number of kisses, the number of hunting days to the number of days of temptation, or the number of feats to the number of obligations?
I would say your answer is "B". Since this is a romantic tale, and this genre is based on a combination of myth, legend, and fable, the number three is always popping up. In "B", the host goes hunting on three different days, and in his absence, his wife attempts to seduce the young knight. Not surprisingly, the Green Knight also swings at Gawain's neck three times--twice to see if Gawain would flinch in fear and once he simply nicks Gawain as a sort of truce and peace offering.
The number three also coincides with the Holy Trinity and the number of times Jesus was tempted by Satan after his forty-day feast. The first time the devil commanded Jesus to change stones into bread, but Jesus refused saying it was not His Father's will. Second, the devil tries to use the Bible against Jesus in order to conquer Him. Jesus told the devil not to test God in such a way. The third time, the devil offered Jesus power. Of course, this temptation also failed.
While Gawain isn't as strong in temptation as Jesus since Gawain lies about the green sash which is meant to protect him from harm, he does prove that he is an honorable knight by admitting his faults and asking forgiveness.