Firms Should Hire Additional Units of a Resource as Long

Firms should hire additional units of a resource as long as the

A) marginal product of the resource exceeds the price of the resource multiplied by the quantity of output produced.
B) marginal product of the resource is less than the price of the resource.
C) price of the output produced is positive.
D) marginal revenue product of the resource exceeds the cost of employing an additional unit of the resource.