Answer:
The correct option is;
C. The only swimmers in the 100-m butterfly race are from the rival swim team
Step-by-step explanation:
The question is a word problem
The given information in the question are;
The names (first and last names) of all the competitors are different
The set, (which are the names) of the swimmers taking part in the 100-m butterfly race = The set (which contains the names) of swimmers from the rival team
Therefore, the only members of the set (the only names in the set) of swimmers taking part in the 100-m butterfly race are (the names of the swimmers from the rival swim team) from the rival swim team.