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: Psychiatry
Drug of choice for bipolar mood disorder - 
Select and explain. 
A. Carbamazepinc, B. Lithium carbonate, C. Imipramine, D. Buspirone
B: Lithium carbonate
Answer: B: Lithium carbonate 
Explanation: None