Task: Text Categorization
Input (English): Question: The arenio ion is a reaction intermediate that is formed in the reactions of: 
 Options:  <0> Electrophilic addition. <1> Electrophilic aromatic substitution. <2> Nucleophilic substitution. <3> Nucleophilic addition. <4> Aromatic nucleophilic substitution.
Output (English): chemistry