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
[{'content': 'On chronic treatment with a drug, patient presents with gingival hyperplasia and facial hirsutism. The drug most likely to cause these side-effects is - \nSelect and explain. \nA. Phenytoin, B. Carbamazepine, C. Valproic acid, D. Phenobarbitone', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Phenytoin", 'role': 'assistant'}]