问题如下图：
选项：
A. 
B. 
C. 
解释：
请问怎么理解the same side of their expect value
NO.PZ2017092702000068问题如下The covarianof returns is positive when the returns on two assets tento:A.have the same expectevalues. B.above their expectevalue fferent times. C.on the same si of their expectevalue the same time. C is correct.The covarianof returns is positive when the returns on both assets tento on the same si (above or below) their expectevalues the same time, incating average positive relationship between returns.当Xi、Yi均同时大于或者均小于X的期望、Y的期望时，COV(X,Y)是正的。 b请问怎么理解？
这题考点是什么呢？答案可以当成结论记吗？谢谢
