Which laws or rules prevent or reduce injury in the event of a crash?
a. passing rules
b. signaling rules
c. impaired-driving laws
d. bicycle helmet laws

The Bicycle helmet law can prevent or reduce injury in the event of a crash. 
Wearing helmet reduce head injury. It is of great importance to wear a helmet, because it can prevent a head injury, and by doing so it can prevent a brain injury. 
The other given laws/rules are laws regarding the drivers.

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