A decision maker can choose the levels of two activities, A and B, so as to maximize net benefits. Activity A costs $100 per unit and activity B Costs $200 per unit. The marginal benefit functions of A and B are MBA 30A - 20B = MBB=-10A + 40B The optimal level of activity A & B are: Select one: a. A = 8 B = 5 b. A = 12 B = 17 C. A = 6 B = 8 d. A = 11 B = 25 e. A = 8 B = 7 O