Researchers were interested in the relationship between how much sleep college students get each night and academic performance. They asked 200 students if they slept 6 or 7 hours each night on average, and then asked everyone for their cumulative GPA (0.0-4.0).

Results showed that there was a weak, positive, non-significant relationship between sleep and GPA.

Why might this be the case?What flaw doyou see in this design?

A. Researchers restricted the range of the variable, sleep.

B. Sleep causes GPA and many other variables too.

C. A sample size of 200 is not large enough to calculate a correlation.

D. Researchers restricted the range of the variable, GPA.