You have 20 cookies total in the jar. The probability of choosing an oatmeal is 4/20, and the probability of choosing a peanut butter cookie is 8/20. In order to find the probability of pulling a peanut butter cookie OR an oatmeal cookie, we have to add the probabilities together. 8/20 + 4/20 = 12/20 or 6/10 or 3/5. The answer is C.
