This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Transplantation, Subject name: Surgery
[{'content': 'Most important HLA for organ transplantation and tissue typing: \nSelect and explain. \nA. HLA-A, B. HLA-B, C. HLA-C, D. HLA-D', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ans. (d) HLA-DRef: Bailey 26th edition, Pages 1409-1412* HLA- A, B, DR are the most important antigens in transplant* HLA antigens are the most common cause of graft rejection* HLA- DR is the most important of all* Anti HLA antibodies causes hyper acute rejection.', 'role': 'assistant'}]