题目内容：
根据下面材料，回答第题：
We can infer from the first paragraph that _______.（ ）
[A] the past central operating assumption conforms to the present condition
[B] the poor in middle-income countries have outnumbered those in Africa
[C] most of the impoverished "bottom billion" have emigrated from Africa
[D] the poor in middle-income countries are quite odd in behavior
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答案解析：