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': 'Drug the choice for hyperthyroidism in first trimester of pregnancy is \nSelect and explain. \nA. Methimazole, B. Propylthiouraril, C. Carbimazole, D. Perchlorate', 'role': 'user'}, {'content': 'Answer: B \nExplanation: Propylthiouracil is the only thioamide which is least teratogenic\xa0and hence it is the drug of choice to hyperthyroidism in pregnancy and lactation.', 'role': 'assistant'}]