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 MHC: 
Select and explain. 
A. Transplantation reaction, B. Autoimmune disease, C. Involved in T-cell function, D. All
D: All
Answer: D: All 
Explanation: A i.e. Transplantation reaction; B i.e. Autommune disease; C i.e. Involved in T -Cell function