When Calculating a Firm's Profit,an Economist Will Subtract Only

When calculating a firm's profit,an economist will subtract only

A) explicit costs from total revenue since these are the only costs that can be measured explicitly.
B) implicit costs from total revenue since these include both the costs that can be directly measured as well as the costs that can be indirectly measured.
C) the opportunity costs from total revenue since these include both the implicit and explicit costs of the firm.
D) the marginal cost since the cost of the next unit is the only relevant cost.