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: Pharmacology
[{'content': 'Which of the following 5-HT3 blockers has highest receptor affinity - \nSelect and explain. \nA. Ondansetron, B. Granisetron, C. Dolasetron, D. Palonosetron', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is 'd' i.e., Palonosetron Palonosetron has maximum affinity for 5HT3 receptor.", 'role': 'assistant'}]