Which of the following statements is true about diversification? a There is no benefit from diversification if the correlation coefficient is 1 b. By diversifying, portfolio risk can be reduced to zero Oc The variance is the weighted average of the individual securities' variances Od. If the covariance between two securities is negative, then the portfolio's standard deviation can be reduced to zero- Oe The benefit from diversification is maximized if the correlation coefficients is zero