How Are Conventions Enforced in Genre Films

How are conventions enforced in genre films?

A) To the letter: Every conventional generic element must be present in the movie for it to be of a particular genre.
B) Strictly: At least five conventional generic elements must be present in the movie for it to be of a particular genre.
C) Obscurely: Only scholars and critics are allowed to deem a movie of a particular genre depending on the conventional elements it incorporates.
D) Perfectly: No genre movie has ever wavered from a set formula.
E) Somewhat: Conventions are not enforced, and while every movie within a particular genre will incorporate some of its elements, few include all conventions.