Answer Choice C

OK all I know since no one will help you, is that Mehran said if you negate D the argument falls apart. Then, I found this argument, When you look at the choices (D) will immediately jump out. This is exactly what we were looking for. The argument assumes that watching violent programs leads to violence during playtime amongst kids. What we need to find is if there is some other reason that could lead to this violence. e.g Do the children who are violent by nature watch violent programs? https://gmatclub.com/forum/when-a-group-of-children-who-have-been-watching-television-programs-th-301634.html but I am assuming maybe answer choice C is saying that if you negate it, it does not nec. make it fall apart. Maybe a person the is a passive observer and also be passive aggressive without violence?

The question is asking you for a necessary assumption, something the author must believe. While C may make the argument stronger, it is not a necessary assumption.