Based on current dividend yields and expected capital gains, the expected rates of return on portfolios A and Bare 12% and 16% respectively. The beta of A is 0.7, while that of Bis 1.4. The T-bill rate is currently 5%, whereas the expected rate of return of the S&P 500 index is 13%. The standard deviation of portfolio A is 12% annually. that of Bis 31 %, and that of the S&P 500 index is 18% a. Calculate the alphas for the two portfolios. (Round your answers to1 decimal place.) 9% Portfolio A Portfolio B % b. If you could invest only in T-bills and one of these portfolios, which would you choose? O Portfolio A O Portfolio B