2909
The relative efficiency of these materials for production of O ( 2 ) and protons under visible light - promoted reactions is evaluated and prolonged reaction lifetimes are observed .
 Chemical: O ( 2 )
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: O ( 2 ) 
Answer:
 Chemical: O ( 2 )