Neuroscientists are making progress in discovering more about the caus

Cause & Effect argument.
P: Neuroscientists-discovering more about the cause of Alzheimer’s disease.
P:Alzheimer’s disease patients suffer from dementia and sever memory loss.
P:Autopsies-presence of brain lesions caused by abnormal protein deposits-similar deposits found in the brains of elderly patients who do not suffer from Alzheimer’s disease.
C:long live-develop Alzheimer’s disease.

WEAKEN


(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.
INCORRECT. pretty much strengthens the argument.

(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.”
INCORRECT. Out of scope. Nothing as such is even mentioned in the passage. Unnecessary information.

(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.
INCORRECT. the procedure was done on dead people, who suffered from alzheimer's and old people because of similarity of lesions in them. If procedure was so easy and accurate, everyone could have found whether they suffer of is going to suffer from alzheimer's.

(D) Autopsies have shown that some people lack the chemical necessary for protein deposits to cause brain lesions.
CORRECT. some people(old/young-anyone) lack chemical for protein deposits to cause brain lesions, not all will suffer from alzheimer's.

(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.
INCORRECT. definition of old is not given in the question. so can't say comes in young/old category.