问一道关于概率的数学题

sunniers

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
答案是C。请赐教。

sunny9653

分母3^3, 分子是3*2*1.
分子：第一次选的时候哪个car都可以坐，第二次只有两个选择了，第三次只剩一个没坐过。
分母：每次都是三个car可以选择。