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: Physiology
Iodine is primarily important in the biochemical synthesis of: 
Select and explain. 
A. ACTH, B. Thyroxine, C. Adrenaline, D. Calcitonin
B: Thyroxine
Answer: B: Thyroxine 
Explanation: None