It can be inferred from Paragraph 4 and Paragraph 5 that ______.

参考解析：

推理判断题。根据第五段第四句和第五句“That makes them slightly happier than traditional men and obviously happier than open-minded women”可知，幸福指数由高到低为：traditional women>traditional men>open minded women>open minded men，因此D项正确；根据第四段第二句中的“a third of Americans have said they’re very happy and about half report being pretty happy”可知，美国大部分人都是幸福的，A项错误；根据第五段第二句“For many years, researchers found that women were happier than men, although recent studies show that the gap has narrowed or may even have changed to the opposite.”可知women并不是一直比men幸福，B项错误；根据第五段第三句“traditional women feel particularly happy: about 40 percent say they are very happy”可知，是40%的traditional women觉得很幸福，并不是40%的美国女人觉得很幸福，C项错误。故选D。