A swim team thinks that the swimsuits and swim caps they use may affect the team's performance. The swim team decides to test if the swimsuits make a difference on how fast they can swim. They split the team in two groups. The two groups wear different kinds of swimsuits and different kinds of swim caps.

Why is their test invalid?


A.The swim team didn't have enough members.
B.They should have changed one variable, keeping the other the same.
C.They all swam different speeds on purpose.
D.Actually, the test is valid.