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
On chronic treatment with a drug, patient presents with gingival hyperplasia and facial hirsutism. The drug most likely to cause these side-effects is - 
Select and explain. 
A. Phenytoin, B. Carbamazepine, C. Valproic acid, D. Phenobarbitone
A: Phenytoin
Answer: A: Phenytoin 
Explanation: Ans. is 'a' i.e., Phenytoin