Dr Yates Forms the Hypothesis That Students Who Sleep More

Dr. Yates forms the hypothesis that students who sleep more prior to taking an exam will score higher on the exam than students who sleep less. Half of the students sleep eight to nine hours the night before the exam. The other half sleep only four to five hours the night before the test. She then gives the participants an exam. In this experiment, what is the dependent variable?

A) The group that sleeps eight to nine hours
B) The performance on the exam
C) The group that sleeps four to five hours
D) Whether they slept four to five or eight or nine hours