For a knowledge test, the highest possible score is 100. A score of 60 has a percentile rank of 40. What does this indicate?

A. A score of 60 means that 40% of the test questions were answered correctly.
B. Sixty students answered 40% of the test correctly.
C. Forty percent of the students earned scores of at least 60.
D. Forty percent of the scores were 60 or less.

Answer: D