Answer:
The following is not a text-organization technique:
A. Genre.
Step-by-step explanation:
Headers, bullet points and numbered lists are techniques used to organize a text in a way that it can be seen more clearly and its ideas can be better organized and distributed.
Genre (the kind of text) is just a category a text belongs to, it is not a part of its organization "on paper". It is more of an abstract thing, whereas the aforementioned techniques can concretely be seen, that is, they are visible parts of a text in terms of structure (regardless of its genre: horror, adventure, essay, etc.).