Which plot element most helps readers determine the theme of a story?
the rising action
the resolution
the exposition
the climax.

the climax

Explanation:

Climax is the term used to refer to the section of story or play in which the tension or action reaches its peak. Sometimes in the story the climax is a point of "crisis." The climax is defined by the high point, and from there the story's action begins to fall before problems are resolved.

"the sandy walls seemed to collapse in on themselves"

and

"the bloodshot waters seemed to have no bottom"