A recent study found that students who participated in extracurricular

 

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The answer is C) There is a correlation between participating in extracurricular activities and academic performance. 

There is nothing we can strongly infer from the study besides that participating in extracurricular activities and higher grades may have a correlation. The other alternatives seem too strong for the few info we are given. 

One cannot guarantee that by participating in extracurricular activities the student will certainly have better grades (they may engage in such activities but study less and therefore will have lower grades) or the other way around (if they do not participate, they will have lower grades because of that). There is no additional information regarding other factors of the study thay could also play a role in this causation (how is their frequency on class, how many subjects they are taking, etc etc). 

Also, we cannot guarantee that extracurricular activities are the only factor: they may already be higher performance students which later choose to participate in extracurricular activities.

Thus, alternatives A, B, D and E are off. 
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