Task: Text Categorization
Input (English): Question: Oxidative phosphorylation involves: 
 Options:  <0> The oxidation of H2O to form O2. <1> Oxidation of O2 to form H2O. <2> The reduction of H2O to give O2. <3> The reduction of O2 to give H2O. <4> None of the above.
Output (English): chemistry