【单选题】

InAmerica, every student in his or her second year of high school is required to take a class in driver’s education.

The course is divided up into two parts: class time for learning laws and regulations and driving time to practice driving.Each student is required to drive a total of six hours. The students are divided up into groups of four. The students and the instructor go out driving for two hour blocks of time. Thus, each student gets half an hour driving time per outing.DriversEd cars are unlike other cars in which they have two sets of brakes, one on the driver’s side and one on the other side where the instructor sits. Thus, if the student driver should run into difficulties the instructor can take over.
After a student has passed the driver’s education course and reached the appropriate age to drive (this age differs in every state but in most cases the person must be 16 years old), he must take his driver’s test. The person must pass all three tests in order to be given a driver’s license. If the person does well in his or her driver’s education class, he or she will pass the test with flying colors and get a driver’s license.
To prevent accidents, a driversEd car______.
A、has a sign inside it
B．has two sets of brakes
C．can’t run very fast
D．is big enough to hold five persons