A. The impact of the Great Depression. B. The shrinking of overseas markets. C. The destruction caused by the First World War. D. The increased exports of European countries. 参考答案:B 答案解析:要点归纳题。引起美国农产品需求量走下坡路的原因应当在第一段第一句中找,“as”即是这因果关系的关键词。A项只是使这一现象加重的原因。C、D则明显与短文内容相悖。