费允杰逻辑讲座中的一道题有疑问

lb1900

3.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.

答案是A. 我认为应该是D。焦点是Senegal and Gambia和Yoruba的人是否是西化的，即目前是否是high-salt diets ？如果他们是西化的，肯定答案是A。但题目中并未说明这些人是西化的。如果不是西化的，那么D中的Yoruba的低盐饮食，保持了低血压，正好和文中的高盐引起高血压形成对应，起到支持作用。

大家以为如何？

shzzhengfan

3.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.

再读下题

lb1900

对。谢谢。

zxppx

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.

基因（已经适应了缺盐的环境）和高含盐量的食物，这两者会使得WB得高血压
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.

说明易于获得盐的人（其基因适应了不缺盐，并且他们的食物中含盐量可能比较高），其血压低。说明盐含量高并不能造成血压高，因为基因已经适应了这样的环境。所以支持文中的假设，是含盐量高和（不适应高盐含量的）基因共同造成高血压的！

(B)The unusually high salt consumption in certain areas of Africa represents a serious health problem.
不知道跟高血压是否有关

(C)Because of their blood pressure levels, most White Africans have markedly decreased their salt consumption.
不能说明WB的情况

(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.
说明缺盐的人（其基因适应了缺盐，并且他们的食物中含盐量低），其血压低。这说明人们之所以血压低，可能是由于基因的作用，也可能是由于食物中的含盐量少，并不能证明两者都其作用，不能支持文中的假设（A）

(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.
反驳假设，指出没区别

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zxppx 发表于 2013-3-20 16:19
Black Americans are, on the whole, about twice as likely as White Americans to develop high blood pr ...

请问A和D的区别在哪？ 为什么A就可以说明是基因和食物含盐量共同决定对的， 而D不行？