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: The oxygen of the ethers as that of the alcohols can be protonated to generate: 
 Options:  <1> Iminium ion. <2> Alkaloxonium ions. <3> Peroxides <4> Piranos. <5> Enaminas
