This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
In Alzheimer's disease which area of brain in involved- 
Select and explain. 
A. Cerebral cortex, B. Hippocampus, C. Cerebellum, D. A + B
D: A + B
Answer: D: A + B 
Explanation: None