Final answer:
The sentence with an antonym clue is the one that contrasts two basketball players' skills using the words 'abysmal' and 'great' with the conjunction 'unlike'.
Step-by-step explanation:
The sentence that contains an antonym clue is: "Jack was abysmal at basketball, unlike Ricky who played great." In this sentence, the word "abysmal" is contrasted with the word "great," providing a clear indication that they are opposites. The usage of "unlike" provides the clue that an antonym is being presented, indicating that Jack's skills are the opposite of Ricky's.