This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General anatomy, Subject name: Anatomy
[{'content': 'Differential cyanosis is seen in \nSelect and explain. \nA. ASD, B. VSD, C. PDA, D. All the above', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ref Harrison 19 th ed pg 1523 Severe pulmonary vascular disease results in reversal of flow through the ductus; unoxygenated blood is shunted to the descending aoa; and the toes--but not the fingers--become cyanotic and clubbed, a finding termed differential cyanosis ). The leading causes of death in adults with patent ductus aeriosus are cardiac failure and infective endocarditis; occasionally, severe pulmonary vascular obstruction may cause aneurysmal dilatation, calcification, and rupture of the ductus.', 'role': 'assistant'}]