The Amount Spent on Textbooks for the Fall Term Was

The amount spent on textbooks for the fall term was recorded for a sample of five hundred university students. The mean expenditure was calculated to be $500 and the median expenditure was calculated to be $425. Which of the following interpretations of the mean is correct?

A) The average of the textbook costs sampled was $500
B) The most frequently occurring textbook cost in the sample was $500
C) 50% of the students sampled had textbook costs equal to $500
D) 50% of the students sampled had textbook costs that were less than $500