Which of these best reveals a story’s theme?
A. the length of the story’s rising action
B. the way the central conflict is resolved
C. the way the characters interact with the setting
D. the relationship between the protagonist and the antagonist

I would say B.

Explanation:

If we think about movies like Joker for example, we can see the setting is very dark and dreary from the beginning. In the first 10 minutes, he cries and gets beat up and the colors are very dull visually to help provide that gloom aesthetic. Later on, the rising action of him killing the two boys didn't change the theme, it just made the story move along. There are a few "antagonists" and he reacts to them poorly. However, the way he resolves the conflict is by just letting himself fall into the chaos. At the end, it shows the theme of how much damage can happen if mental illness is not treated the way it's supposed to even though through Arthur's (Joker's) point of view he thinks the moral is "it doesn't get better for people like me".