Which of the following statements best describes the optimal capital structure and why? a. The optimal capital structure is the mix of debt, equity, and preferred stock that maximizes the company's earnings per share (EPS). b. The optimal capital structure is the mix of debt, equity, and preferred stock that maximizes the company's stock price. c. The optimal capital structure is the mix of debt, equity, and preferred stock that minimizes the company's cost of equity. d. The optimal capital structure is the mix of debt, equity, and preferred stock that minimizes the company's cost of debt. e. The optimal capital structure is the mix of debt, equity, and preferred stock that minimizes the company's cost of preferred stock