Benny is trying to determine the optimal capital structure of firm Bluebird. The firm's capital structure consists of debt and common stock. To estimate the cost of debt, the company has produced the follow table: The firm's tax rate, T, is 35%. The company uses the CAPM to estimate its cost of common equity, rs. The risk-free rate is 4% and the market risk premium is 7%. Benny estimates that if it had no debt its beta would be 1.2. What is the firm's WACC under an optimal capital structure? 11.37% 10.81% 11.92% 10.55%