Final answer:
A personal essay is the most appropriate format for this prompt as it allows the writer to share a personal experience and reflect on its significance.
Step-by-step explanation:
The most appropriate format for a response to this prompt would be a personal essay. A personal essay allows the writer to share a personal experience and reflect on its significance. In this case, the prompt asks the writer to describe a time when someone helped them unexpectedly and explain why it was meaningful. Through a personal essay, the writer can provide details, emotions, and insights that would engage the readers.
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