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': 'In which of the following phases of clinical trial of drug ethical clearance is not required - \nSelect and explain. \nA. Phase I, B. Phase II, C. Phase III, D. Phase IV', 'role': 'user'}, {'content': "Answer: D \nExplanation: Ans. is `d i.e., Phase IV o 'Phase 4' of clinical testing is a phase of post marketing surveillance and is undeaken on the basis of result of phase 1, 2 and 3. This phase occurs only after 'FDA Safety Review', 'ADA submission' and finally WDA approval' and hence does not require ethical clearance.", 'role': 'assistant'}]