There is a 25% that Clarissa will choose oatmeal. That is because there are 4 options that can be chosen at random. So the probability to choose any of the meals would be 25%.
No, Clarissa is NOT correct. The probability of picking oatmeal at random is 1/4 because she has 4 choices, and she has the same probability for all the choices. Lets divide so you can understand better:-