In efficient markets, profit opportunities are quickly eliminated as they develop.

In a perfectly competitive market, all firms in the long run earn:

A) positive economic profit. B) positive accounting profit. C) zero economic profit. D) zero accounting profit.

Suppose that each worker must use only one shovel to dig a trench, and shovels are useless by themselves. In the long run, the firm's cost function is

A) TC = (w/r) ? q. B) TC = (w + r)/q. C) TC = (w + r). D) TC = (w + r) ? q.