A monopolistic firm has a sales schedule such that it can sell 31 prefabricated garages per week at $5,100 each, but if it restricts its output to 30 per week it can sell these at $5,200 each. The ___?
a) Marginal cost of production is $5,100
b) Marginal revenue is $5,100
c) Marginal revenue is $100
d) Marginal cost of production is $5,200