<prompt> In which of the following phases of clinical trial of drug ethical clearance is not required -Phase IPhase IIPhase IIIPhase IV  <response>: 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. 