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': 'Which of the following antitubercular drugs are associated with hypothyroidism? \nSelect and explain. \nA. Ethionamide, B. Streptomycin, C. PZA, D. Rifampicin', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Ethionamide is thought to prevent organification of iodine in thyroid hormone synthesis, as it is structurally related to other thionamides (propylthiouracil and methimazole). So, it can lead to hypothyroidism.', 'role': 'assistant'}]