6281
Activation - induced cytidine deaminase ( AID ) is a DNA mutator enzyme essential for adaptive immunity .
 Chemical: cytidine
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
 Entities: cytidine 
Answer:
 Chemical: cytidine