题目
For two random variables (possibly dependent), X and Y, an upper bound on the covariance of X and Y is:
选项
A.σ_X σ_Y
B.0
C.1
D.there is no upper bound unless the variables are independent
答案
A
解析
本题解析如下：「huixue_img/importSubject/1564169385952808960.png」