Based solely on the information given, do you have reason to question the results of the following hypothetical study? Explain your reasoning. In a study designed to determine whether bicyclists who wear helmets have fewer accidents, researchers tracked 500 riders with helmets for one month.

A.
Yes, there is reason. The sample is biased; riders who do not use helmets should also be included.
B.
No, there is not reason. The goal of the study is clear.
C.
No, there is not reason. There is no bias in the study.
D.
Yes, there is reason. The variables that were measured are not identified.
E.
Yes, there is reason. It makes sense that riders who do not use helmets get into more accidents.
F.
No, there is not reason. It is unlikely that there are any confounding variables in the study.