Which of the following statements correctly relate to M&M Proposition I, with taxes? I. Debt decreases the value of a firm. II. The levered value of a firm exceeds the firm's unlevered value. III. The weighted average cost of capital (WACC) is constant. IV. The optimal capital structure is zero debt.

I and IV only

II only

II and III only

I only

I, III, and IV only