While the ultimate cause or causes of Alzheimer's disease are still unknown, ----.
A) other non-genetic causes have also been studied in relation to the causes of this disease
B) vitamin E, which is an antioxidant, can be of benefit for people with this disease
C) a person with the disease may forget the names of family members
D) there are several risk factors that increase a person's likelihood of developing the disease
E) the symptoms of this disease begin gradually, usually with memory lapses