This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Pharmacology, Subject name: Pharmacology
In which phase post marketing surveillance is done: 
Select and explain. 
A. Phase I, B. Phase II, C. Phase III, D. Phase IV
D: Phase IV
Answer: D: Phase IV 
Explanation: Ans. D. Phase IVPhase - 1 first in human. Done for toxicity and pharmacokinetic studies. Phase - 2 mainly done for safety and efficacy. Phase- 3 done on large number of patients detecting the efficacy. Phase -4 is post marketing surveillance done which detect the rare side effects which were not detected in above phases.