can you explain how and why please

9. Mikkelson Corporation's stock had a required return of 11.75% 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 remain unchanged. What is the company's new required rate of return? (a) 14.38% [ri]=r6+Bi([rm]r6) (b) 14.74% (c) 15.11%. (d) 15.49%. (e) 15.87%