This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Respiratory system, Subject name: Anatomy
Cyanosis NOT improving with 100% oxygen in case of 
Select and explain. 
A. Cardiac asthma, B. Interstitial lung disease, C. Bronchial asthma, D. Tetrology of hea
D: Tetrology of hea
Answer: D: Tetrology of hea 
Explanation: Presence of cyanosis that does not improve with supplemental oxygen suggest true pathological cardiac or pulmonary shunting of blood . Ref Harrison 19th edition pg 1248-49