This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Pharmacology
[{'content': 'in clinical trails whats the duration of PHASE IV ? \nSelect and explain. \nA. 3-5 years, B. 1-3yrs, C. 1yr, D. indefinite duration of time', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Clinical Trials phase 1 = Safety, ADME, Healthy bioactivity, volunteers or subj. w/ drug-drug interaction indications Length (per phase) 20-80 6-12 mos phase 2 = Sho-term side Subjects with effects & efficacy indications Several hundred 1-2 yrs phase 3= Safety & efficacy Basis for labeling, new formulations New indications, QoL, surveillance Subjects with Hundreds-indications thousands Subjects with indications 2-3 yrs phase 4 = Safety & efficacy Basis for labeling, new formulations New indications, QoL, surveillance Subjects with Hundreds-indications thousands Subjects with indications indefinite time and on going ref : kd tripathi 8th ed', 'role': 'assistant'}]