A Firm Hires Labor, Capital, and Land to Produce Grapefruits

Multiple Choice

A firm hires labor, capital, and land to produce grapefruits. Currently the marginal product of the last unit of labor input is 40, the marginal product of the last unit of capital input is 60, and the marginal product of the last unit of land input is 200. The market wage is $20 and the market price for capital is $30. If the firm is using the optimal combination of inputs, then the price of land is

A) $4.
B) $40.
C) $100.
D) indeterminate from the given information.