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
The fastest acting antithyroid drug is: 
Select and explain. 
A. Lugol's iodine, B. Radioactive iodine, C. Propylthiouracil, D. Sodium thiocyanate
A: Lugol's iodine
Answer: A: Lugol's iodine 
Explanation: None