This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Other topics and Adverse effects, Subject name: Anatomy
Mechanism of action of propylthiouracilin hypehyroidism is: 
Select and explain. 
A. Inhibition of organification of iodine, B. Inhibition of oxidation of iodine, C. Inhibition of coupling of two DIT residues, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: (Ref: KDT 6/e p248) Propylthiouracil, carbimazole and methimazole act by inhibiting the enzyme, thyroid peroxidase. It catalyses: Oxidation of iodine Organification Coupling