Ron Has Alzheimer's Disease

Ron has Alzheimer's disease. He frequently forgets doctor's appointments and almost started a fire in his kitchen because he forgot a pan on the stove. Recently, his son was concerned because Ron blamed him for stealing his car keys when Ron simply forgot where he put them. What phase of Alzheimer's disease is Ron in?

A) Ron is in the early phase of Alzheimer's disease.
B) Ron's Alzheimer's disease has progressed beyond the early phases and he may no longer be able to care for himself.
C) Ron's Alzheimer's disease has progressed to the point that he absolutely cannot care for himself and will need 24-hour assistance.
D) Ron has reached the final phase of Alzheimer's disease.