Romeo and Juliet are individuals, not groups. Letter B is also mentioning individuals. Letter C is about abstract concepts. For us to have a conflict between groups as the outline suggests, we need two groups and that's what we have in option D. Montagues and Capulets are family names, each having many people carrying the same name. They're family groups. Also, in the Play (Romeo and Juliet), the two families hate one another.
