How do we find p(rolling 2 or 5) with one number cube?

The sample space of the rolling the cube is 6.
 The probability of rolling 2 in a cube is 1. So p(2) is 1/6
Similarly the probability of rolling 5 in cube is 1.
 So, p(5) = 1/6
To find p (2 or 5) which is p(2) + p(5)
p(2) + p(5) = 1/6 + 1/6 which is 2/6.
2/6 can be reduced to 1/3.
  so right answer is 1/3

In all honesty, there really is no “work” per say to show. mainly it’s just using the process of elimination. the question is asking which domain(s) would be the most appropriate for the function c(n). n is the number of observed vehicles so right away, 1, 2, and 3 can be eliminated.why? 1, 2 start in the negatives and therefore it is impossible to observe negative cars. so, #4 would be the best answer to the given problem.