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
Which is the drug of choice for maintenance therapy in uncomplicated bipolar disorder ? 
Select and explain. 
A. Sodium valproate, B. Carbamazepine, C. Lithium, D. Lamotrigine
C: Lithium
Answer: C: Lithium 
Explanation: None