(单选题)

What can we learn from the passage? ( )

A.Different IQ tests have been led to the same results.

B.A rise in IQ scores during the 20th century occurred around the world.

C.The falling of IQ scores since the 1975 returned to 99.4.

D.Changes in IQ scores are related with external factors.

参考答案：D

参考解析：

推断题，A项：不同的测试结果都一样，表达明显错误；B项：二十世纪全球IQ测试值上升，定位至第七段a clear increase in IQ scores during the 20th century throughout the Western world.可知并非“全球”，而是“西方世界”；C项根据第五段But the scores began dropping for men born after 1975. By 1989, the average IQ score had returned to 99.4.可知并非1975年之后就回归到99.4，表达错误；D项：IQ数值的变化受外部因素影响，根据第九段He concluded that external factors probably influenced the scores more than genetics.可推知确实与外部因素有关。故本题正确答案选D。

知识点：推断题英语阅读理解通用英语