Definition: 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.
Input: Question: The metal that appears most frequently in the active site of metalloproteases is: 
 Options:  <0> Calcium. <1> Magnesium. <2> Selenium. <3> Sodium. <4> Zinc.
Output:
chemistry