[求助]诚心请教:LAST--1-1-8

求助]诚心请教AST--1-1-8

8.     Neuroscientists are making progress in discovering more about the cause of Alzheimer’s disease. Alzheimer’s disease patients suffer from dementia and sever memory loss. Autopsies performed on such patients have revealed the presence of brain lesions caused by abnormal protein deposits. Similar deposits are also found in the brains of elderly patients who do not suffer from Alzheimer’s disease. It follows that everyone who lives long enough will eventually develop Alzheimer’s disease.

Which one of the following statements, if true, most seriously undermines the conclusion that everyone who lives long enough will eventually develop Alzheimer’s disease?

(A) The lesions found in the brains of non-Alzheimer’s disease patients are far less extensive than those found in the brains of Alzheimer’s disease patients.

(B) The developing brain produces a greater number of cells than it will ever use. The extra cells are later destroyed by what biologists call “programmed cell death.”

(C) The procedure that allows scientists to discover the presence of protein deposits during an autopsy is not yet refined enough to ensure detection of the lesions in all patients.

(D) Autopsies have shown that some people lack the chemical necessary for protein deposits to cause brain lesions.

(E) Though most Alzheimer’s disease patients develop the disease when they are in their late fifties to early seventies, the frequency of patients who develop the disease in their forties is on the rise.

请问为什么是D呢?这题的逻辑思路是什么?

其他为什么错?

非常感谢!

Premise: There is a coincidence of Alzheimer's disease and leisions. Leisions are caused by abnormal protein deposits. There is another coincidence of such deposits and elderly patients who are not suffering from Alzheimer's disease.

Conclusion: Everyon who live long enough will eventually develop Alzheimer's disease.

Here I want to ask some questions. (1) Can you know whether those healthy elderly (not patients) have abnormal protein deposits? (2) Can you infer that leisions cause Alzheimer's disease from the coincidence of them?

If either of your answers to the two questions is 'NO', the conclusion in the stem cannot perfectly be drawn from the premise.

In my opinion, D is a counterargument from the perspective of question (1). Because D says that there are some people who are unlikely to develop the deposits.

谢谢NN详细指点！