It is Friday when Pooh, Haley, and Walt have the same test to take on the following Wednesday. Pooh stays up very late each night, even though he has to wake up early each morning, and crams for the test on Tuesday night. Haley stays up late on the weekend, but also studies for the test each and gets plenty of sleep on Monday and Tuesday nights. Walt gets 9 hours of sleep during each night and starts studying for the test on Sunday.

What is the best approach for Pooh, Haley, and Walt to increase their test reliability?

A. To adjust their schedules so that they can study together.

B. To ask the teacher to move the test to Friday.

C. To stay up late studying every night they can.

D. To get more sleep, start studying earlier, and ask the teacher how to study for the test.