A certain roller coster 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 coster. if a certain passenger is to ride the roller coster 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
Can please someone explain the thought process for the answer?
source: GMAT prep