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
Drug having very narrow therapeutic range is: 
Select and explain. 
A. Lithium, B. Sertraline, C. Roboxetine, D. Dothiepin
A: Lithium
Answer: A: Lithium 
Explanation: None