Standard Deviation Is an Important Concept in Portfolio Theory Because

Multiple Choice

Standard deviation is an important concept in portfolio theory because:

A) it is a measure of risk for a stock when it is held on a stand-alone basis.
B) it is a measure of risk for a stock when it is held in a diversified portfolio.
C) it is a measure of the variability of a stock's return.
D) Both a. and c. are correct
E) All of the above are correct