Critical Reasoning (CR) | Re: Wunderlich Park has a strict regulation that requires mountain

Wunderlich Park has a strict regulation that requires mountain bicyclists to wear helmets. Recently, a group of bicyclists acknowledged that helmets may prevent injuries to the wearer, but protested claiming the park should only regulate activities that may hurt a third party. Hence, the bicyclists argued that they should have the right to refrain from wearing helmets.

Which of the following, if true, most seriously weakens the conclusion in the passage?

We need to say that the bicyclists should not
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