What does the experiment mentioned in Paragraph 4
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What does the experiment mentioned in Paragraph 4 prove?
A. There are more enzymes in decaf drinkers’ urine sample.
B. There are more melatonin concentrations in caffeine drinkers’ urine sample.
C. Decaf drinkers produce less melatonin.
D. Caffeine drinkers produce less sleep hormone.
热搜：第4腰椎怎么定位
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答案：D
第四段是第三段实验的继续，是该实验的第二个阶段。研究人员通过对志愿者尿样进行化验发现，咖啡因摄入者体内的褪黑激素仅为非咖啡因摄入者的一半。褪黑激素就是睡眠激素，所以，答案应该选D。