A. To what extent does ingested aluminum make its way to the brain? -
+ve - If a great extent of ingested aluminum makes its way to the brain, then the conclusion is right. (i.e ingesting small particles of aluminum is the cause for the disease and banning aluminum cookware will help to reduce the no of new patients)
-ve - However if none or negligible amount of ingested aluminum makes its way to the brain (i.e The aluminum accumulation is not because of what you eat and it is due to some other process) then banning aluminum is not going to be of any effect. The conclusion is wrong. Based on the answer to this question. The argument is either strengthened or weakened. Hence this helps in the evaluation of the conclusion.

B. Does Alzheimer’s disease lead to the development of aluminum deposits in the brain? - Cause and effect is interchanged.
+ve - If yes, then development of aluminum is the effect and not the cause so the conclusion is wrong
_ve - If no, then the conclusion is right

C. Do elderly individuals without Alzheimer’s disease typically have high levels of aluminum in their brains?
+ve - If Yes, It means presence of aluminum is not the cause for the disease and the conclusion is wrong
-ve - If no, then the conclusion is right

D. Do Alzheimer’s patients in countries where aluminum cookware is not used have high levels of aluminum in their brains?
+ve - If yes, Then the aluminum in the brain is not due to the cookware and the conclusion is wrong
-ve - If no, then the conclusion is right

E. Do patients in earlier stages of Alzheimer’s have lower levels of aluminum in their brains than patients with advanced Alzheimer’s?
Whether +ve or -ve, does not affect the argument as it is talking about the levels of aluminum in patients and not whether the cookware is the cause. Hence irrelevant - Correct