A Monopolist's Marginal Expenditure Is

A monopolist's marginal expenditure is

A) The extra benefit from hiring or purchasing the marginal unit of an input, per marginal unit
B) The extra cost incurred to hire or purchase the marginal units of an input, per marginal unit
C) The difference between the marginal cost and benefit from hiring the marginal unit of an input, per marginal unit
D) The total cost incurred to hire or purchase all units of an input in the production process