The most logical conclusion to this story, given the theme of good sportsmanship, would be:
B. Nell exposes the lie and proves that Hamish is innocent, allowing the friends to compete against each other.
This option aligns with the theme of good sportsmanship by emphasizing honesty, integrity, and the importance of fair play in competition. By standing up for her friend and ensuring that the best competitor wins fairly, Nell demonstrates the values of true sportsmanship.