I can see this like the checkboxes for language preferences in DF settings. You could have them like: "Big pulls", "small pulls", "First time tank/dps/heal" "Lore exploration" and so on.

However, the cynic in me can't help but agree with Driavna's first post. It's similar to how people check all the language checkboxes in the DF settings to curb their queue time. I don't know the logistics of Group A and C but if we were to pretend for a minute that there's way more people in Group A than C, the latter would probably select all the preferences if they find their queue time unbearable.