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
True about Alzheimer's disease -a) Mutation in APP geneb) Autoantibodyc) Aluminium is a risk factor  d) Viral infection has increased riske) Hereditary 
Select and explain. 
A. abc, B. ad, C. acd, D. bde
C: acd
Answer: C: acd 
Explanation: None