求助一道GWD1上的一道数学题

Q2:

A certain roller coaster has 3 cars, and a passenger is equally likely to ride in any 1 of 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

我每次碰到有关概率的题目就很头疼，请问有没有这方面的专门讲解和练习的？