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': 'Commonest type of congenital cyanotic heart disease: \nSelect and explain. \nA. Atrial septal defect, B. Ventricular septal defect, C. Tetralogy of Fallot, D. Patent ductus arteriosus', 'role': 'user'}, {'content': 'Answer: C \nExplanation: None', 'role': 'assistant'}]