A researcher wants to examine the effect of noise level on reading comprehension. He finds that regardless of the noise level, all participants tested received the maximum scores for their performance. The results may be due to _____ effect.

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

The ceiling effect refers to when all participants in a study score at or near the maximum possible score, indicating a lack of variability in the dependent variable. In this case, regardless of the noise level, all participants received the maximum scores for their reading comprehension performance, suggesting that the noise level did not have any effect on their performance.