This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: General Pharmacology, Subject name: Pharmacology
In drug metabolism, hepatic cytochrome P-450 system is responsible for: 
Select and explain. 
A. Phase I reactions (hydrolysis, oxidation, reduction etc.) only, B. Phase II reactions (conjugation, synthesis etc.) only, C. Both phase I and II reactions, D. Converting hydrophilic metabolites to lipophilic metabolites
A: Phase I reactions (hydrolysis, oxidation, reduction etc.) only
Answer: A: Phase I reactions (hydrolysis, oxidation, reduction etc.) only 
Explanation: Ans. (A) Phase I reactions (hydrolysis, oxidation, reduction etc. only(Ref: Katzung 13th/e p60; KDT 8th/e p32)Cytochrome P450 enzymes are responsible for phase I reactions only whereas microsomal enzymes can be involved in phase II also (glucuronide conjugation)