Critical Reasoning

A proposed ordinance requires that all cyclists wear a helmet when riding a bike. However, one cycling enthusiast argued that since more than ninety percent of bike-related accidents do not cause more than a scrape, mandatory helmet use would only marginally decrease the number of serious injuries caused by cycling.

Which of the following, if true, would most seriously weaken the cycling enthusiast's argument?

A. Most cyclists do not currently own bike helmets.

B. The cost of buying a proper bike helmet is significantly less than possible medical costs due to injury.

C. Helmets have not proven useful in preventing head trauma in biking accidents since the force of the accident often causes the helmet to fall off.

D. In the city where the ordinance was proposed, the number of injuries due to bike accidents was less than the national average.

E. Most of the serious injuries resulting from bike accidents occur due to head trauma.

OA is E

I was able to narrow it down to B and E but ended up choosing B. Can some please explain why B is wrong?

Thanks

Kushal