This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: All India exam, Subject name: Anatomy
The first step in alcohol metabolism by the liver is the forma on of acetaldehyde from alcohol, a chemical reaction catalyzed by 
Select and explain. 
A. Cytochrome P450, B. NADPH-cytochrome reductase P450, C. Alcohol oxygenase, D. Alcohol dehydrogenase
D: Alcohol dehydrogenase
Answer: D: Alcohol dehydrogenase 
Explanation: .