This question is incomplete. Here's the complete question.
Read What Is the Horror Genre?, by Sharon A. Russell
What are the categories Russell proposed are best for analyzing the horror genre?
Answer:
Russel explains that one way to categorize the horror genre is by whether a story deals with parallel worlds or with seemingly supernatural events that have natural explanations in the end.
Another categorization could be based on the sources of horror (inside or outside a person).
The different themes are also a possible categorization.
Step-by-step explanation:
Russel states that categorizing horror stories by its subjects is a mistake because not all of them have monsters.