This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: G.I.T, Subject name: Pharmacology
[{'content': 'Morphine should not be used in: \nSelect and explain. \nA. Ischaemic pain, B. Biliary colic, C. Cancer pain, D. Post-operative pain', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Ans. B. Biliary colicOpioids have potent analgesic effect via mu, kappa receptor. They are known to increase the intrabilliary pressure by constricting the smooth muscle. Therefore, they are contraindicated in biliary colic.', 'role': 'assistant'}]