As an investor, you are trying to calculate the WACC for a company that only has privately issued debt (i.e. you are unable to look up the cost of debt). Of the following options which is not a viable method to estimate the required return on debt? O Observe the average debt cost for firms with the same credit rating O Interview a lender that has knowledge of the company's industry O Observe the cost of debt for similar firms in similar risk classes O Use the 5 year average interest rate of 30 year U.S. Government debt