In which of the following phases of clinical trial of drug ethical clearance is not required -

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.