There are several important information's already given in the question. Based on those information's the answer can be easily deduced.
In the first case, The amount of chicken the chef cooks for 36 people = 9 pounds Then The amount of chicken the chef cooks for 1 person = 9/36 = 1/4 pounds Now let us take the second case The amount of chicken the chef cooks for 68 people = 17 pounds Then The amount of chicken the chef cooks for 1 person = 17/68 = 1/4 pounds From the above deductions, it can be concluded that the correct option among all the options given in the question is the third option or option "C".