Final answer:
The excerpt that best shows the author's regret is the one that describes the profound melancholy and offense he feels that the organ player is forgotten during the cold months.
Step-by-step explanation:
The excerpt that best shows the author regretted that he forgot about the organ player in the cold months is:
profound melancholy-it offended him that the links should lie in enforced fallow-ness, haunted by ragged sparrows for the long season...