Assume large-company stocks returned 13.1 percent on average over the past 15 years. The risk premium on these stocks was 7.8 percent and the inflation rate was 5.1 percent. What was the average risk-free rate of return for those 15 years?

Select one:

a. 12.90 percent

b. 13.30 percent

c. 5.30 percent

d. 8.00 percent

e. 21.92 percent