6. are the most vulnerable roadway users.
a. pedestrians and bicyclists
b. motorcyclists
c. slow-moving vehicles
d. vehicles towing trailers

A. Pedestrians and bicyclists. They are the most vulnerable because they have little or no protection if they are struck by a motorized vehicle. Slow-moving vehicles (such as farm equipment) and vehicles towing trailers account for plenty of accidents. The National Agriculture Safety Database notes that as many as two out of three highway accidents involve a slow-moving vehicle. But those vehicles and their drivers are not the ones in a vulnerable position -- the weight and size of such vehicles protects their operators. The National Highway Traffic Safety Administration reported that in 2015, 5,376 pedestrians and 818 bicyclists lost their lives in crashes where they were hit by a motor vehicle. That was 18% of the traffic fatalities reported in that year..