When labor is the only input a firm uses, the marginal cost of a unit of output can be defined as
a. the marginal revenue multiplied by the wage.
b. the marginal product of labor multiplied by the wage.
c. the wage divided by the marginal product of labor.
d. the marginal product of labor divided by the wage.

Option (C) is the correct option.

Explanation:

Correct option: the wage divided by the marginal product of labor.

If there is a single factor of production or input employed in the production of certain commodity such as labor then the marginal cost of producing a unit of output is equal to the wage rate or price of labor divided by the marginal productivity of labor.

Marginal productivity of labor is the value added to a output by an additional hired labor.

Therefore, When labor is the only input a firm uses, the marginal cost of a unit of output can be defined as the wage divided by the marginal product of labor.

answer(d) all of the choices are correct;

answer///supply is elastic, and demand is inelastic;