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
Differential cyanosis occurs in which disease 
Select and explain. 
A. Severe caorctation, B. Inturrupted aoic arch, C. PPHN, D. All of the above
D: All of the above
Answer: D: All of the above 
Explanation: Blood flow to lower extremities decrease in PPHN,coarctation of aoa, interrupted aoic arch. Ref : Ghai essential of pediatrics, eighth edition, p.no:432