What occurs in a crossover effect that is not readily explained by a rival hypothesis? a.            The control group performs better at pretesting, but the experimental group performs better at post...

What occurs in a crossover effect that is not readily explained by a rival hypothesis?

a.            The control group performs better at pretesting, but the experimental group performs better at post testing.

b.            The control group shows no change.

c.             The experimental group starts higher.

d.            The experimental group increases at a faster rate.