Final answer:
The definitive answer to why Annie decided to go over Niagara Falls in a barrel is not present in the provided text, but a common literary theme suggests a mix of adventure, financial need, and self-proving motivations.
Step-by-step explanation:
The best answer that summarizes Annie's reason for going over Niagara Falls in a barrel in Queen of the Falls is not directly available in the provided excerpts. However, based on similar historical contexts and the typical motivations depicted in such stories, one could postulate that Annie's decision might have been driven by a desire for adventure, financial gain, or proving oneself in the face of societal expectations. Without the specific text of Queen of the Falls, we can't provide a definitive answer, but we can make educated guesses based on common themes in literature involving stunts and human endeavor.