系统解析:细节理解题。Children in the schools with fountains, increased their water consumption from about 3 up to 4 glasses a day, while those in the other schools continued to drink an average of 3 glasses. Over the research, the number of overweight kids upped from 384 to 385 out of 1,641 at the schools with water fountains. In comparison, the number of overweight kids at the other schools increased from 339 to 364 out of 1,309, Dr. Muckelbauer said.句意为:用饮水机的学生增加了他们水的消耗量从大约三杯到了一天四杯,而其它学校的学生他们的饮水量仍然是平均三杯,但前者在1641个学生里面增学生总数从384到了385个,而后者没有安装饮水机的学校学生在1309名学生中,增胖的总数从339个上升到了364个。所以本自然段讲的是研究的结果,故答案应为D。