The historical rate of return on stock A was regressed on the rate of return of stock M (the explanatory variable). The slope of the regression line was 0.8, the standard deviation of the residuals was 0.3 and the standard deviation of the rate of return of M was 0.2. What was the standard deviation of the rate of return on A? Multiple Choice 0.460 0.340 O O O 0.286 O none of the above