Which statement about portfolio diversification is correct?

The risk-reducing benefits of diversification do not occur meaningfully until at least 50-60 individual securities have been purchased.

Proper diversification can eliminate systematic risk.

Typically, as more securities are added to a portfolio, total risk would be expected to decrease at a decreasing rate.

Proper diversification can eliminate systematic risk and increase return.

Because diversification reduces a portfolio's total risk, it necessarily reduces the portfolio's expected return