This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Diseases of Thyroid, Subject name: Medicine
What is the most common cause of hypothyroidism world-wide? 
Select and explain. 
A. Hashimoto thyroiditis, B. Subacute thyroiditis, C. Silent thyroiditis, D. Iodine deficiency
D: Iodine deficiency
Answer: D: Iodine deficiency 
Explanation: Most common cause of hypothyroidism worldwide is IODINE DEFICIENCY In case of Iodine sufficiency most common cause of hypothyroidism : Autoimmune disease (Hashimoto Thyroiditis) and iatrogenic.