This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Environment & Nutritional Pathology, Subject name: Pathology
A severely depressed 32-year-old man commits suicide by running his car motor in his closed garage for several hours. The mechanism of death in this case of carbon monoxide (CO) poisoning is through which of the following mechanisms? 
Select and explain. 
A. Displacement of oxygen on hemoglobin by CO, B. Hepatocellular necrosis, C. Inhibition of protein synthesis, D. Inhibition of the respiratory chain enzymes
A: Displacement of oxygen on hemoglobin by CO
Answer: A: Displacement of oxygen on hemoglobin by CO 
Explanation: CO combines with hemoglobin with an affinity 240 times greater than that of oxygen to form carboxyhemoglobin. At concentrations above 50% carboxyhemoglobin, cerebral anoxia, coma, convulsions, and death ensue. The other choices do not reflect the strong binding affinity of CO for hemoglobin.Diagnosis: Carbon monoxide poisoning