This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Central Nervous system, Subject name: Pharmacology
[{'content': 'The following ADR is seen with \nSelect and explain. \nA. Phenytoin, B. Valproate, C. Barbiturate, D. Carbamazepine', 'role': 'user'}, {'content': 'Answer: A \nExplanation: The picture shows gingival hyperplasia caused by phenytoin Ref: KDT 7th ed Pg: 417-422', 'role': 'assistant'}]