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
Study state plasma concentration is achieved after? 
Select and explain. 
A. 2 t1/2, B. 3 t1/2, C. 4 t1/2, D. 5 t1/2
D: 5 t1/2
Answer: D: 5 t1/2 
Explanation: Ans. is 'd' i.e., 5 t%