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: Pharmacology
The thyroid inhibitor which produces the fastest response is 
Select and explain. 
A. Lugol's iodine, B. Propylthiouracil, C. Radioactive iodine, D. Lithium carbonate
A: Lugol's iodine
Answer: A: Lugol's iodine 
Explanation: IODINE AND IODIDES Though iodine is a constituent of thyroid hormones, it is the fastest acting thyroid inhibitor. Ref:- kd tripathi; pg num:-254