From Jan. 1, 1940 to Jan. 1, 2040, the historical average annual rate of return in the hypothetical country of Westeros was 18%. The annual standard deviation of the rate of return is 30%. What is the upper bound of the 95.4% confidence interval for the annual rate of return based on this information? Select one: a. 13% b. 21% c. 15% d. 24% e. 12%