Which of the following statements is INCORRECT?

A: The company's cost of capital is the expected rate of return that investors demand from the company's assets and operations.

B: The WACC is the required rate of return on the firm''s average-risk investments.

C: The WACC is the minimum acceptable return that a firm has to earn on its investments in order to provide an acceptable return to its security holders.

D: An increase in a firm's debt ratio will have no effect on the required rate of return for equity holders.