This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: FMGE 2017, Subject name: Pharmacology
[{'content': 'Mechanism of action of Pemetrexed is:- \nSelect and explain. \nA. RNA synthesis inhibitor, B. Dihydrofolate reductase inhibitor, C. Dopamine agonist, D. Topoisomerase inhibitor', 'role': 'user'}, {'content': "Answer: B \nExplanation: Dihydrofolate reductase Inhibitors Methotrexate Pralatrexate Pemetrexed PEMETREXED - used in mesothelioma D: Topoisomerase introduces negative coil's and aids in replication IRINOTECAN - topoisomerase Inhibitor", 'role': 'assistant'}]