In perfect capital markets, ________.

a. A company’s WACC does not change as it changes its capital structure

b. A company can lower its WACC by using more debt in its capital structure

c. A company can lower its WACC by using more equity in its capital structure

d. A company’s cost of debt capital is exactly equal to its cost of equity capital when the company uses 50% debt and 50% equity in its capital structure