Brian won a scholarship for four years of college. During these four years Brian could also do any number of things, including:

I. Travel the World for four years II. Working for making money III. Take job training for a better job

Which of the following is the opportunity cost of Brain attending college? (5 points)

a. Zero. b. II only. c. The sum of I, II, III, and any other opportunities he passed up. d. Whichever of I, II, III or any other opportunities he passed up is most valuable to him.