16207
Vitamin A metabolite retinoic acid ( RA ) plays a major role in the aging adult brain plasticity .
 Chemical: Vitamin A; Chemical: retinoic acid
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: Vitamin A, retinoic acid 
Answer:
 Chemical: Vitamin A; Chemical: retinoic acid