Rachel Is Interested in Math Skills of Boys Versus Girls

Rachel is interested in math skills of boys versus girls in the sixth grade.She administers a series of math problems to both groups and asks them to solve as many problems as they can within a 15-minute period.She finds that both groups were only able to answer only 2% of the problems.Rachel's results may be due to a _____ effect.

A) performance
B) maximum
C) ceiling
D) floor