Suppose a Firm Sells Its Product in a Competitive Market

Suppose a firm sells its product in a competitive market. If the ongoing wage rate in a competitive labor market is $30 and the market price of a firm's product is $2, then which of the following statements is true?

A) The firm should continue to hire workers until the marginal product of the last worker hired is 2 units.
B) The firm should continue to hire workers until the marginal product of the last worker hired is 5 units.
C) The firm should continue to hire workers until the marginal product of the last worker hired is 10 units.
D) The firm should continue to hire workers until the marginal product of the last worker hired is 15 units.