Jenna takes a survey of students in her class to determine how many hours they studied for their Math exam. The mean of the responses is 5.6 hours. Which conclusion MUST be true?
A) No one in the class studied more than 5 hours.
B) Every member of the class studied for the exam.
C) At least one person in the class studied 1 hour.
D) At least one person in the class studied more than 5 hours.