og3,对og解释的疑问，请大家一定帮忙

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3. The average life expectancy for the United States population as a whole is 73.9 years, but children born in Hawaii will live an average of 77 years, and those born in Louisiana, 71.7 years. If a newlywed couple from Louisiana were to begin their family in Hawaii, therefore, their children would be expected to live longer than would be the case if the family remained in Louisiana.

Which of the following statements, if true, would most significantly strengthen the conclusion drawn in the passage?

A. As population density increases in Hawaii, life expectancy figures for that state are likely to be revised downward.

B. Environmental factors tending to favor longevity are abundant in Hawaii and less numerous in Louisiana.

C. Twenty-five percent of all Louisianans who move to Hawaii live longer than 77 years.

D. Over the last decade, average life expectancy has risen at a higher rate for Louisianans than for Hawaiians. B

E. Studies show that the average life expectancy for Hawaiians who move permanently to Louisiana is roughly equal to that of Hawaiians who remain in Hawaii.

If B is true, the greater abundance of longevity-promoting environmental factors it mentions is probably at least partly responsible for the higher life expectancy in Hawaii. Children born in Hawaii benefit from these factors from birth, and thus Louisianans who have children in Hawaii increase their children’s chances of living longer. Therefore, B is the best answer.

If life expectancy in Hawaii is likely to be falling, as A says, the argument is weakened rather than strengthened. C and E, in the absence of other relevant information, have no bearing on the conclusion; thus, they are inappropriate. D is irrelevant, because the information it mentions about rates would already have been incorporated into the statistics cited in the passage.

按照OG对D的解释，D中所说的rates已经包括在提干中了，是提干中信息的重复。可是，提干中没有提到关于rates的相关内容，不明白og的解释