What is the relation of genetics to Alzheimer’s disease?

a. Identified genes have a strong effect on early-onset Alzheimer’s disease and a weaker effect on lateonset disease.

b. Identified genes have a weak effect on early-onset Alzheimer’s disease and a stronger effect on lateonset disease.

c. Identified genes have a strong effect on both the early and late onset forms of Alzheimer’s disease.

d. Identified genes have little or no effect on Alzheimer’s disease, regardless of time of onset.