Security A has an expected return of 7%, a standard deviation of returns of 3.5%, a correlation coefficient with the market of -0.3%, and a beta coeficient of 0.5. Security B has an expected return of 12%, a standard deviation of returns to 10%, a correlation with the market of 0.7 and a beta coefficient of 1.0. In a diversified portfolio, which security is the least risky? In a single-asset portfolio which would be the least risky? Why?