As the number of securities in a portfolio is increased, what happens to the average portfolio standard deviation?14/31 As the number of securities in a portfolio is increased, what happens to the average portfolio standard deviation?It decreases at an increasing rate.It increases at an increasing rate.It increases at a decreasing rate.It first decreases, then starts to increase as more securities are added.It decreases at a decreasing rate Giải thíchChọn đáp án E