QUESTION 20 3 points Save Answer Which statement about portfolio diversification is correct? O a Proper diversification can reduce or eliminate systematic risk. O b. The risk-reducing benefits of diversification do not occur meaningfully until at least 15-20 individual securities have been purchased. O c. Because diversification reduces a portfolio's total risk, it necessarily reduces the portfolio's expected return. O d. Typically, as more securities are added to a portfolio, total risk would be expected to fall at a decreasing rate