which of the following statements is false?

a. we should select u.s. treasury securities whose maturity is equal to our investment horizon and use the yield on that treasury security as our risk-free rate.

b. to estimate a stock's equity beta, we can regress the historical excess returns of the market portfolio on the historical excess returns of that individual stock, the resulting regression coefficient is the estimate of the stock's equity beta.

c. survey shows most large firms and financial analysts use the yields of long-term (10- to 30-year) bonds to determine the risk-free interest rate.

d. none of the above