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
Commonest type of cong. cyanotic hea disease is 
Select and explain. 
A. ASD, B. VSD, C. TOF, D. PDA
C: TOF
Answer: C: TOF 
Explanation: 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