[PhysicsBowl question revised] A car and a truck are both traveling with a constant speed of 30 m/s. The car is 20 m behind the truck. The truck driver suddenly applies his brakes, causing the truck to slow to a stop at the constant rate of 3 m/s². 3 seconds later, the driver of the car applies their brakes and just manages to avoid a rear-end collision. Determine the constant rate at which the car slowed. 
选项为:A:9.23 m/s²  B:10.33 m/s²  C:11.23 m/s²  D:11.93 m/s²  请回答其中一个选项.