Six people—Julio, Kevin, May, Norma, Olivia, and Tamio—participate in a track meet. Two of them enter the marathon, two enter the relay, and two enter the sprint.
Each participant enters only one event.
If Kevin enters the marathon, then both Julio and May enter the relay, and if both Julio and May enter the relay, then Kevin enters the marathon.
If Norma does not enter the sprint, then Tamio enters the relay.
If Olivia enters the relay, then Julio does not enter the relay.
Olivia and Tamio do not both enter the relay.
If both Kevin and Olivia enter the relay, then which one of the following must be true?