Which Two of the Following Options Correctly Give Rules for Portfolio

Which two of the following options correctly give rules for portfolio management according to mean- variance portfolio theory?

A) Portfolio standard deviation is less than the weighted average risk of the individual investments, except for perfectly positively correlated investments.
B) Portfolio returns are a weighted average of the expected returns on the individual investments.
C) Portfolio standard deviation is greater than the weighted average risk of the individual investments, except for perfectly negatively correlated investments.
D) Expected returns are a weighted average of the portfolio return on the group of investments.