This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Medicine
A 38-year-old woman develops palpitations, weight loss, and heat intolerance. On examination, she has a mild tremor, an enlarged thyroid, and resting tachycardia. Biochemical tests confirm the diagnosis and she is started on methimazole. Which of the following is the most likely mechanism of this drug? 
Select and explain. 
A. inhibition of iodine uptake, B. inhibition of thyroidal organic binding and coupling reactions, C. lowering serum calcium, D. adrenal suppression
B: inhibition of thyroidal organic binding and coupling reactions
Answer: B: inhibition of thyroidal organic binding and coupling reactions 
Explanation: Methimazole is an effective treatment for hyperthyroidism. Methimazole interferes with thyroid function mainly by inhibition of thyroidal organic binding and coupling reactions. In contrast to other agents such as perchlorate, the action of thioamides is not prevented by large doses of iodide.