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': 'MHC class - III genes encode \nSelect and explain. \nA. Complement component C3, B. Tumor necrosis factor, C. Interleukin-2, D. Beta-2 microglobulin', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Structure - Major histocompatibility complex, (HLA) complex MHC class III genes encode Complement components C2 and C4 Properdin factor B of alternate pathway TNF - alpha and beta Heat shock proteins Also known as "complement region"', 'role': 'assistant'}]