Most common cause of hypehyroidism-: (A) Thyroid hyperplasia, (B) Thyroid adenoma, (C) Thyroid carcinoma, (D) Grave disease
Answer is D. Most common cause of hypehyroidism is Graves' disease - 76% followed by Toxic Multinodular goitre - 14% and Toxic Solitary thyroid adenoma - 5%. Reference : page 740 Davidson's Principles and practice of Medicine 22nd edition