As far as alzheimer's researchers know, the primary cause of alzheimer's disease is:
a. deterioration of neurons that produce the neurotransmitter acetylcholine.
b. pruning or deterioration of unused neurons over the life span.
c. normal aging, although accelerated in some individuals.
d. a lack of education or stimulation earlier in life, compounded by obesity.

a. deterioration of neurons that produce the neurotransmitter acetylcholine.

Explanation:

Alzheimer's disease -  

It is a disease associated with memory , it is a type of dementia .

The initial stages of the disease is the remember new things , the day to day task becomes very difficult with time .

During this disease the neurons get deteriorated day by day , which are responsible to produce the acetylcholine .

Hence , the correct statement about Alzheimer's disease is ( a ) .