If a Researcher Finds a Negative Correlation Between the Number

If a researcher finds a negative correlation between the number of hours that students play computer games and grades, this means that

A) computer game playing causes a decrease in grades.
B) computer game playing causes an increase in grades.
C) lower grades cause a student to be disinterested in studying and more interested in playing computer games.
D) an experiment would have to be performed to establish a cause-and-effect relationship between video game playing and grades.