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: Medicine
[{'content': 'Most common cause of Acquired Complete Hea Block in children is \nSelect and explain. \nA. Cardiac Surgery, B. Acute Rheumatic Fever, C. Drug overdose, D. Myocarditis', 'role': 'user'}, {'content': "Answer: A \nExplanation: Ans. is 'a' i.e., Cardiac Surgery Post surgical third degree A-V block resulting from trauma to the A-V node at operation is the most common cause of acquired A-V block in children", 'role': 'assistant'}]