4. The following table is given for the information of the stock A, stock B, stock C, and the market index: The expected return, volatility, and the correlation between individual stock and market index is presented in the table below: Expected return Volatility Correlation with the market index Stock A 12.0% 20.6% 0.7170 Stock B 16.5% 15.6% 0.6722 Stock C 12.4% 16.5% 0.7553 Market index 10.0% 10.5% The annual effective risk-free rate is 2%. (a) [4 points) Calculate the required rate of the returns for each individual stock. (b) (2 points) Calculate the alpha of each individual stock. And determine whether the investor is recommended to buy of sell the stock