Exception Style missing from Settings/General

In Settings/General under the Catalog heading, one of the carts I'm working with doesn't have the Exception Style option. Is there some place I'm supposed to enable that in order for it to show in this area? I need to add some forbidden combinations and they aren't showing in the options or in the product general tab. There is no Options/Settings Heading. I'm sure I'm missing something…

Thanks for your help!