This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Urology, Subject name: Surgery
[{'content': 'The causal mechanism in carcinoid syndrome is due to \nSelect and explain. \nA. Erythropoietin and immunoglobulin, B. Serotonin and bradykinin, C. Insulin and insulin like substances, D. ACTH and ACTH like substances', 'role': 'user'}, {'content': "Answer: B \nExplanation: Carcinoid syndrome develops (in 10% of carcinoid tumours) due to release of 5-HT (serotonin), kinins, prostaglandins, histamine and indoles causing flushing, diarrhoea, cyanosis, asthmatic attacks, hepatomegaly, cardiac lesion on right side.. Reference : page 878 SRB's manual of surgery 5th edition", 'role': 'assistant'}]