Answer:
B.) The relative sizes of the total market capitalizations for each kind of security that the firm issues.
Explanation:
WACC is the weighted average cost of capital. It is used as the discount rate when evaluate projects whose risk are similar to company's risk. Calculation of WACC uses relative market values of common equity, preferred stock and debt to calculate each proportion. Cost of equity, cost of preferred stock and aftertax cost of debt are also used. This makes choice B correct.