Final answer:
A person struck by a vehicle at 30 mph is 40% more likely to be killed compared to being struck at 25 mph due to the higher energy involved at the faster speed.
Step-by-step explanation:
A person struck by a vehicle moving at 30 mph is more likely to be killed than a person struck by a vehicle moving at 25 mph. The correct answer, based on the information given and studies on the fatality risks at different impact speeds, would be option (b) 40%. Studies have shown that increasing the speed limit from 25 mph to 30 mph does increase the fatality risk significantly. This increase in risk is due to the higher energy involved in the collision at higher speeds, which results in more severe injuries.