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: Gynaecology & Obstetrics
[{'content': 'Half life biological of oxytocin: \nSelect and explain. \nA. 2-3 min, B. 3-4 min, C. 5-6 min, D. 7-8 min', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Oxytocin\n\nIt is a nonapeptide (Peptide of nine amino acids).\nReleased by posterior pituitary and synthesized in the supra optic and paraventricular nucleus of hypothalamus.\nHalf life 3–4 minutes.\nDuration of action – 20 minutes.\nMechanism of action – Acts through calcium mediated channels to initiate myometrial contractions.', 'role': 'assistant'}]