Following is information on the production levels of three different firms. Firm A is currently producing at a quantity where it is experiencing increasing returns. Firm B is currently producing at a quantity where it is experiencing diminishing returns. Firm C is currently producing at a quantity where it is experiencing negative returns.

a. If each of the firms cut back on its labor force, what will happen to its marginal product of labor? Why?

b. If each of the firms adds to its labor force, what will happen to its marginal product of labor? Why?