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: Pediatrics
Most common cause of thyrotoxicosis in childhood ? 
Select and explain. 
A. Toxic nodular goitre, B. Toxic adenoma, C. Graves disease, D. Thryotoxicosis factitia
C: Graves disease
Answer: C: Graves disease 
Explanation: None