The Increased Risk of Car Accidents for Drivers Talking on a Cell

The increased risk of car accidents for drivers talking on a cell phone

A) results primarily from using one hand to simply hold one's cell phone.
B) is no greater than the risk for drivers chatting with other passengers.
C) is no greater than the risks for drivers listening to a car radio.
D) is equally great for those using handheld and those using hands-free phones.