Suppose for Each Student in a Statistics Class, You Record

Short Answer

Suppose for each student in a statistics class, you record how far he/she sits from the teacher during a particular class session and his/her score on that day's quiz.
(No explanations are necessary for the following questions.)
a. Students who sit closer to the teacher tend to score higher on the quiz. Would you expect the correlation coefficient between distance and quiz score to be positive, negative, or close to zero?
b. The correlation coefficient between distance and quiz score turns out to be close to -1. Would that prove that sitting close to the teacher causes higher quiz scores?
c. There is really no association between distance and quiz score. Would you expect the correlation coefficient to be positive, negative, or close to zero?
d. There is really no association between distance and quiz score. Is it still possible to calculate a correlation coefficient?