def format_prompt(example):
    return (
        f"{example['question']}\n"
        f"A. {example['choices'][0]}\n"
        f"B. {example['choices'][1]}\n"
        f"C. {example['choices'][2]}\n"
        f"D. {example['choices'][3]}\n"
        "Answer: "
    )
# Trailing space in "Answer: " encourages a single-letter next token