Porter Plumbing's stock had a required return of 11.50% last year, when the risk-free rate was 5.50% and the market risk premium was 4-75%. Then an increase in investor risk aversion caused the market risk premium to rise by 2%. The risk-free rate and the firm's beta reman nchange what is t he company's new required rate of return? (Hint: First calculate the beta, then find the required return.) Select the correct answer. O a. 14.03% b. 13.93% O c. 14.1390 d. 14.23% O e. 14.33%