$($c$)$ The following are convolution kernels. Select those that can smooth an image.

Convolution kernels:

$A=([1,1,1],[0,0,0],[-1,-1,-1]),B=([1,1,1],[1,5,1],[1,1,1]),C=([1,0,-1],[1,0,-1],[1,0,-1])D=([-1,-1,-1],[-1,9,-1],[-1,-1,-1])$

$[4$ marks$]$