This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Immunology, Subject name: Microbiology
[{'content': 'HLA III gene codes for - \nSelect and explain. \nA. Immunological reaction in graft rejection, B. Complement, C. Graft versus host reaction, D. Immunoglobulins', 'role': 'user'}, {'content': 'Answer: B \nExplanation: HLAs corresponding to MHC class III encode components of the complement system. Ref: Ananthanarayanan & Panikers textbook of microbiology 9th edition pig: 140', 'role': 'assistant'}]