This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General pathology, Subject name: Pathology
[{'content': 'The given site encodes \nSelect and explain. \nA. Complement component C3, B. Tumor necrosis factor, C. Interleukin-2, D. Beta-2 microglobulin', 'role': 'user'}, {'content': 'Answer: A \nExplanation: MHC class III genes encode*Complement components C2 and C4*Properdin factor B of alternate pathway*TNF - alpha and betaHeat shock proteinsReference: Harrison&;s Principles of Internal Medicine; 19th edition', 'role': 'assistant'}]