After graduating from high school, Steve had three choices, listed in order of preference: (1) matriculate at our campus, (2) work in a printed circuit board factory, or (3) attend a rival college. His opportunity cost of going to college here includes which of the following?

a. the cost of books and supplies at the rival college

b. the income he could have earned at the printed circuit board factory plus the direct cost of attending college here (tuition, textbooks, etc.)

c. the benefits he could have received from going to the rival college

d. only the tuition and fees paid for taking classes here