The public is well aware that high blood cholesterol levels raise the risk of stroke caused by blood clots. But a recent report concludes that people with low blood cholesterol levels are at increased risk of the other lethal type of stroke-cerebral hemorrhage, caused when a brain artery bursts. The report suggests that because blood cholesterol plays a vital role in maintaining cell membranes, low blood cholesterol weakens artery walls, making them prone to rupture. The conclusion thus supports a long-standing contention by Japanese researchers that Western diets better protect against cerebral hemorrhage than do non-Western diets.
The argument is based on which one of the following assumptions
A．Western diets are healthier than non-Western diets.
B．Western diets result in higher blood cholesterol levels than do non-Western diets.
C．High blood cholesterol levels preclude the weakening of artery walls.
D．Cerebral hemorrhages are more dangerous than strokes caused by blood clots.
E．(E) People who have low blood pressure are at increased risk of cerebral hemorrhage.
参考答案：B
解析： 由本题段落中的论述可知，高的血液胆固醇水平能防止脑溢血，西方饮食比非西方饮食能更好地防止脑溢血。因此我们很容易推出西方饮食比非西方饮食容易使人产生高的血液胆固醇水平是本题的结论所依赖的假设，亦即(B)是正确答案；(C)是本题提及的低的血液胆固醇水平会削弱动脉血管的强度的否命题，原命题正确，否命题不一定正确，因此(C)不是本题的结论依赖的假设；选项(A)、(D)和(E)都不能从本题的论述中推出，因此都是错误的选项。