【正确答案】 B

【答案解析】
The coefficient of variation, CV=standard deviation/arithmetic mean, is a common measure of relative dispersion (risk). CV₁=0.4/0.3=1.33; CV₂=0.6/0.6=1; CV₃=4.8/1.3= 3.69; and CV₄=5.2/1.7=3.06. Because a lower CV means lower relative risk, Security 2 has the lowest relative risk and Security 3 has the highest relative risk.