This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: C.V.S, Subject name: Pediatrics
[{'content': 'Commonest type of cong. cyanotic hea disease is \nSelect and explain. \nA. ASD, B. VSD, C. TOF, D. PDA', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Most common cyanotic hea disease is tetrology of fallot encountered beyond the age of 1 yr constituting almost 75% of all blue patient. Ref : Ghai essential pediatrics,eighth edition, P.no:420', 'role': 'assistant'}]