This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Medicine
[{'content': '100% Oxygen is not effective in: March 2005 \nSelect and explain. \nA. Pulmonary edema, B. MI, C. Tetralogy of fallot, D. COPD', 'role': 'user'}, {'content': 'Answer: C \nExplanation: Ans. C: Tetralogy of fallot', 'role': 'assistant'}]