Hardmon Enterprises is currently an all-equity firm with an expected return of 13.6%. It is considering borrowing money to buy back some of its existing shares. Assume perfect capital markets.

a. Suppose Hardmon borrows to the point that its debt-equity ratio is 0.50. With this amount of debt, the debt cost of capital is 4%. What will be the expected return of equity after this transaction?

b. Suppose instead Hardmon borrows to the point that its debt-equity ratio is 1.50. With this amount of debt, Hardmon's debt will be much riskier. As a result, the debt cost of capital will be 6%. What will be the expected return of equity in this case?

c. A senior manager argues that it is in the best interest of the shareholders to choose the capital structure that leads to the highest expected return for the stock. How would you respond to this argument?