22918
Copper induces apoptotic cell death through reactive oxygen species - triggered oxidative stress in the intertidal copepod Tigriopus japonicus .
 Chemical: Copper; Chemical: oxygen
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: Copper, oxygen 
Answer:
 Chemical: Copper; Chemical: oxygen