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
A patient is brought to the casualty in the state of altered sensorium. He was on Lithium treatment for affective disorder and has suffered through an attack of epileptic fits. On examination he has worsening tremors, increased DTR's and incontinence of urine. He has also undergone an episode of severe gastroenteritis 2 days ago. The serum Lithium was found to be 1.95 meg/Lit. The probable cause for his present state is: 
Select and explain. 
A. Lithium toxicity, B. Dehydration, C. Manic Episode, D. Depressive Stupor
A: Lithium toxicity
Answer: A: Lithium toxicity 
Explanation: A i.e. Lithium toxicity