Refer to the study in the previous question (question 3).

The study finds that the group of students who drink regular cola has a significantly higher average test score than the group who drink caffeine-free cola. This implies:
A. The difference in the average test score between the regular cola group and the caffeine-free cola group is so large that it can be explained by chance.
B. The difference in the average test score between the regular cola group and the caffeine-free cola group is so small that it can be explained by chance.
C. The difference in the average test score between the regular cola group and the caffeine-free cola group is so small that it cannot be explained by chance.
D. The difference in the average test score between the regular cola group and the caffeine-free cola group is so large that it cannot be explained by chance.