What Does the Expected Value-Standard Deviation Rule Fail to Provide

What does the expected value-standard deviation rule fail to provide?

A) The size of the return on investment.
B) The risk associated with undertaking the investment.
C) A decision rule that always distinguishes between two investment opportunities.
D) The expected value of the returns of an investment if standard deviations are known.
E) A rule for investments whose returns are distributed along the normal curve.