anyone whose brain cells are susceptible to injury will eventually develop Alzheimer's disease a decline in testosterone level puts one at increased risk for Alzheimer's disease whether a person develops Alzheimer's disease is dependent entirely on the level of beta-amyloid in his or her brain only people with Alzheimer's disease are at risk for injury to brain cells
The hormone testosterone protects brain cells from injury and reduces levels of the protein beta-amyloid in the brain. Beta-amyloid causally contributes to Alzheimer' s disease, and people whose brain cells are susceptible to injury are probably more susceptible to Alzheimer' s disease. So there is reason to think that__.
Which one of the following most logically completes the argument?