Julie Finds That the Number of Hours She Sleeps Each

Multiple Choice

Julie finds that the number of hours she sleeps each night is related to the scores she receives on quizzes the next day.As her sleep approaches eight hours,her quiz scores improve; as her sleep drops to five hours,her quiz scores show a similar decline.Julie realizes that:

A) there is a negative correlation between the number of hours she sleeps and her quiz grades.
B) there is a positive correlation between the number of hours she sleeps and her quiz grades.
C) her low quiz scores are caused by sleep deprivation the night before a quiz.
D) she should sleep about 10 hours a night to ensure 100 percent quiz grades.