During winter, Thendo made the decision to attend winter school which precludes her from her winter job which she normally earns R6 500 and spends R500 on transport. Thendo's tuition cost is R4 500, books and supplies cost R500. The opportunity cost of attending winter school is. a) R 12 000 b) 5 000 c) R 7 000 d) R 11 500