If $x,y,z$ are three real numbers and if $x>y$ and z is a negative number then the following correct one is 

$x=4;y=3;z=-5$

$4>3$

A: $xz=4\times \left(-5\right)=-20yz=3\times \left(-5\right)=-15$

$\therefore xz<yz.$ So A is in correct.

B: $xz<yz$ correct

C: Both A and B is incorrect

D: A is incorrect