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: Physiology
[{'content': 'Carbon dioxide retention is seen in all, except \nSelect and explain. \nA. Carbon monoxide poisoning, B. Respiratory failure, C. Ventilator failure, D. Pulmonary edema', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Symptoms of carbon monoxide poisoning is as same as the case of hypoxia. Respiratory failure leads to alveolar hypoventilation leads to retention of CO2 and reduced lung compliance (Alveolar edema) also leads to CO2 retention.', 'role': 'assistant'}]