Use the rules of expected value to show that cov(ax+b,cy+d)=accov(x,y).

A) cov(ax+b,cy+d)=accov(x,y)
B) cov(ax+b,cy+d)=ac+bd
C) cov(ax+b,cy+d) = a2c2 cov(x,y)
D) cov(ax+b,cy+d)=acvar(x,y)