You will be given a definition of a task first, then some input of the task.
In this task, you are given a question and answer options for that question. Using this information, you have to classify each text into different topics: medicine, nursery, psychology, chemistry, pharmacology, biology.

Question: In what type of reaction does the cytochrome P-450 of the liver typically intervene? 
 Options:  <0> Hydration. <1> Reduction. <2> Hydrolysis. <3> Esterification <4> Hydroxylation
Output:
chemistry