Suppose that index model for Stocks A and B is estimated from excess returns with the following results: Ra= 0.04+0.6Rm+ea, Rb= -0.04+1.3Rm+eb, Risk on the market is 30%, R-squared of A is 30%, R-squared of B is 40%, security A residual variance is Select one: O a. 656 O b. 856 O c. 756 O d. 556