The most logical conclusion to the story, given the theme of good sportsmanship, would be:
a. Nell exposes the lie and proves that Hamish is innocent, allowing the friends to compete against each other.
This option aligns with the values of fairness, integrity, and camaraderie that are central to good sportsmanship. By defending Hamish and ensuring that he is not wrongfully disqualified, Nell upholds the spirit of competition and their friendship.