[求助]！！大全-3-19

19. 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 predisposition in westernized Blacks may reflect an interaction between western high-salt diets and genes that adapted to an environmental scarcity of salt.

Which of the following statements about present-day, westernized Black Africans, if true, would most tend to confirm the researchers’ hypothesis?

(A) The blood pressures of those descended from peoples situated throughout their history in Senegal and Gambia, where salt was always available, are low.

(B) The unusually high salt consumption in certain areas of Africa represents a serious health problem.

(C) Because of their blood pressure levels, most White Africans have markedly decreased their salt consumption.

(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.

(E) No significant differences in salt metabolism have been found between those people who have had salt available throughout their history and those who have not.

请问这道题的应该怎么推理。我觉得答案没有解释两个因素之间的interaction.

文中说的意思是这种倾向(黑人通常比白人血压高，即黑人血压高的倾向)是由于西方高盐饮食和为适应无盐环境而发展的基因之间的相互作用的结果。

要加强推理，就用实事加强：

要么基因是在无盐环境下发展的，则血压高；

要么基因是在有盐环境下发展的，则血压低。

因为现在西方化的黑人的高盐饮食是一定的。

谢谢les的解答，不好意思一直没有时间上网。

相当于是举了个反例，对吗？

题目说高血压是由于适应无盐环境的基因和有盐的饮食造成

则举反例说在有盐环境下形成的基因不会造成高血压。

是应该这样理解吗？

Right!

ＬＥＳ　ＭＭ　解释得真好。佩服ｉｎｇ。