I see that you've gotten some different answers, so I want to provide some additional context about the terms you're questioning.
First, you can't truly determine a story's climax without first considering its protagonist and conflict.
The protagonist of a story faces some key conflict by an antagonist. He or she typically (but not always) undergoes a change as a result of the conflict.
In this story, Ponyboy is the protagonist. He's the narrator, so the plot that develops is through his perspective. He faces conflict through the Socs as a whole and specifically through Bob and Randy, who have beaten up Johnny in the past. When Bob tries to drown Pony, Johnny kills Bob, thus setting in motion the central plot of the story.
Thus, the rising action follows. Pony and Johnny flee the scene and escape to a remote church where they have some freedom to live a life uncomplicated by Socs and Greasers. Although they are in hiding, this period represents a time of relative peace for both boys. This peace ends...
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