argument (about) whether?

[enydia]

Hello, Teachers.

In the following sentence, is the prep 'about' necessary?

There is an argument (about) whether violence displayed in the media is related to subsequent violent vehaviour among viewers.

Someone told me that it's an error to place a clause after a preposition. But I usuall see some wh-clauses after prepositions. It seems that that-clauses never go after prepositions, do they? It would be very nice if you could provide some explanation about this grammar point for me.

Thank you in advance.

Enydia ;)

[Tdol]

It doesn't work without it IMO.

[enydia]

It doesn't work without it IMO.

Thank you, Teacher Tdol.

Do the following two sentences work?

There is an argument that violence displayed in the media is related to subsequent violent vehaviour among viewers.
There is an argument about that violence displayed in the media is related to subsequent violent vehaviour among viewers.