向大神求助如何解答这题！

Diicoooo

                                                                                                                                                                                                [size=10.000000pt]89.[size=10.000000pt]Black Americans are, on the whole, about twice as likely as White Americans to develop high blood pressure. This likelihood also holds for westernized Black Africans when compared to White Africans. Researchers have hypothesized that this predisposiaon in westernized Blacks may reflect an interacAon between western highJsalt diets and genes that adapted to an environmental scarcity of salt.
                                                [size=10.000000pt]Which of the following statements about presentJday, westernized Black Africans, if true, would most tend to confirm the researchers' hypothesis?
                                                [size=10.000000pt](A) The blood pressures of those descended from peoples situated throughout their history in Senegal and Gambia, where salt was always available, are low.
                                                [size=10.000000pt](B) The unusually high salt consumpAon in certain areas of Africa represents a serious health problem.
                                                [size=10.000000pt](C) Because of their blood pressure levels, most White Africans have markedly decreased their salt consumpAon.
                                                [size=10.000000pt](D) Blood pressures are low among the Yoruba, who, throughout their history, have been situated far inland from sources of sea salt and far south of Saharan salt mines.
                                                [size=10.000000pt](E) No significant differences in salt metabolism have been found between people who have had salt available throughout their history and those who have not.
  
正确答案为a




我理解猜想的内容是条件a高盐饮食和b.....的基因之间的这种interaction导致高血压的原因。但是我觉得正因为如此，选c而不是选a。
求大神能给出详细的解析。

                               
                       
               

cycgundam

这道题的关键是定位一个逻辑联系：饮食（盐）与基因（受到环境中盐储量多少影响）的联系。

C是错误，因为C提及饮食，没有提及基因或者影响该基因的盐储环境。

我一开始以为是D，后来想想A更好。D虽然提及了盐储环境，但是提及的确实样本没有在这个环境里面（因为Yoruba的生存范围里没有盐）。所以逻辑上D也没有提及盐储环境（只有字面上提及）。试想，如果Yoruba的生存环境里不存在盐，又如何证明受到盐储量环境影响的基因和饮食会有联系呢？

最后最可信的答案只有A。

本题应该算高分题，最大的陷阱就是学者的假设中并没有提及这个interaction是正面（两者同增长）还是负面（一者增长，另一种减少），而只是提及有这么一个interaction。所以只要选项中对这个interaction有过逻辑上的提及，那么就是正确选项。