Final answer:
The best summary of Annie's stunt is her journey from initiating the stunt, going over the falls in the barrel, and being safely rescued afterward, despite the injuries. The correct answer is option d.
Step-by-step explanation:
The best summary of what happens when Annie performs her stunt in Queen of the Falls is the second response provided. It encapsulates the entire event from Annie's departure on the boat, her nerve-racking journey over the falls inside the barrel, to the moment she is rescued, bruised but alive. This response captures the anticipation, the actual stunt, and the aftermath succinctly covering all essential aspects of the story.