8034
Several enzymes and synthetic bioinorganic systems perform the activation of C - H bonds in methane and small hydrocarbons , mediated by transition metal mononuclear centers .
 Chemical: C - H; Chemical: methane; Chemical: hydrocarbons; Chemical: transition metal
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: C - H, methane, hydrocarbons, transition metal 
Answer:
 Chemical: C - H; Chemical: methane; Chemical: hydrocarbons; Chemical: transition metal