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
At toxic doses, zero order kinetics is seen in: 
Select and explain. 
A. Penicillin, B. Phenytoin, C. Valproate, D. Carbamazepine
B: Phenytoin
Answer: B: Phenytoin 
Explanation: None