8. Neuroscientists are making progress in discovering more about the cause of Alzheimerâ€™s disease. Alzheimerâ€™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 Alzheimerâ€™s disease. It follows that everyone who lives long enough will eventually develop Alzheimerâ€™s disease.
Which one of the following statements, if true, most seriously undermines the conclusion that everyone who lives long enough will eventually develop Alzheimerâ€™s disease?
(A) The lesions found in the brains of non-Alzheimerâ€™s disease patients are far less extensive than those found in the brains of Alzheimerâ€™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 â€œprogrammed cell death.â€