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: Microbiology
[{'content': 'Complement attaches to immunoglobulin at ? \nSelect and explain. \nA. Aminoterminal, B. Fab region, C. Variable region, D. Fc fragment', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Fc fragment . Fc fragment is composed of the carboxyterminal. It determines the biological activity such as complement fixation, placental transfer, skin fixation and catabolic rate. CH-2 of Ig G and CH, of IgM bind to C1q poion of CI.", 'role': 'assistant'}]