Of the Following, Which Is Most Likely an Example of a Correlational

Of the following, which is most likely an example of a correlational study?

A) A study that shares the typical symptoms of repeated sports concussions in high school athletes.
B) A study that relates the pre- and post- concussion memory scores in a group of athletes.
C) A study that breaks down the number of sports concussions by sport played and number of years played.
D) A study that tests the effects of a concussion training program on number of concussions.