To investigate whether the consumption of beetroot juice enhances exercise performance, a researcher selected a random sample of 50 student athletes from all the student athletes at a college. The athletes in the sample were randomly assigned to one of two groups. In one group, 25 athletes were given a daily dose of beetroot juice, and in the other group, the remaining athletes were given a daily dose of a placebo. At the end of six weeks of exercise training, the resear her compared the performances of the two groups. Based on the design of the  investigation, which of the following is the largest population to which the results can be generalized? 
选项为:A:The 25 student athletes assigned to the beetroot juice group  B:The 50 student athletes in the sample  C:All student athletes at the college  D:All students at the college  E:All people who exercise  请回答其中一个选项.