When a natural monopoly exists in a given industry, the per-unit costs of production will be?

The stock is currently selling for $17.75 per share, and its noncallable $3,319.97 par value, 20-year, 1.70% bonds with semiannual payments are selling for $881.00. the beta is 1.29, the yield on a 6-month treasury bill is 3.50%, and the yield on a 20-year treasury bond is 5.50%. the required return on the stock market is 11.50%, but the market has had an average annual return of 14.50% during the past 5 years. the firm's tax rate is 40%.refer to exhibit 10.1. what is the best estimate of the after-tax cost of debt? a. 6.07%