一道GWD数学题（在讨论帖里找不到）

Q2:

A certain roller coaster has 3 cars, and a passenger is equally likely to ride in any 1 of the 3 cars each time that passenger rides the roller coaster.  If a certain passenger is to ride the roller coaster 3 times, what is the probability that the passenger will ride in each of the 3 cars?

A.        0

B.        1/9

C.        2/9

D.        1/3

E.        1