If a Psychologist Tests Whether There Is Any Difference Between

Multiple Choice

If a psychologist tests whether there is any difference between how fast people work in the morning versus how fast they work in the evening,the null hypothesis is that

A) people who work in the morning work faster.
B) people who work at night work faster.
C) there is a difference in worker speed,but no prediction is made.
D) there is no difference in the speed at which people work.