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: Does not block the flow of electrons in oxidative phosphorylation: 
 Options:  <1> Cyanide. <2> Antimycin A. <3> CO. <4> 2,4-DNP. <5> Amital.
