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: Surgery
[{'content': "Most common cause of Thyroiditis is - \nSelect and explain. \nA. Reidl' s Thyroiditis, B. Subacute Thyroiditis, C. Hashimoto's Thyroiditis, D. Viral thyroiditis", 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]