Parent category identification problem

I want to display a snippet when post is in specific categories.
I have categories A, B , C, D and want to display “How r u” when posts belong to Categories A and B. Also, if the post belongs to sub-categories in A and B.

I used the code

if ( in_category(array('A,'B')))
{
echo "How r u";
	}

It works fine but if the post is in sub-category of A or B it does not work. I do not wish to hardcode the sub-category names as I might add few more sub-categories.
Is there a way I can check direct parent and display what I want.