Definition: In this task, you are given a multiple-choice question about healthcare. Answer the question based on your information and classify your answers into '1', '2', '3', and '4'.
Input: Question: Which of the following enzyme complexes catalyzes the reduction of molecular oxygen to water during oxidative phosphorylation? 
 Options:  <1> ATP synthase. <2> Cytochrome c oxidase. <3> NADH-Q oxide-reductase. <4> Q-cytochrome c-oxide-reductase. <5> Succinate-Q reductase.
