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 determination of dissolved oxygen in natural water samples, using the Winkler method, is based on the previous oxidation of Mn (II) in an alkaline medium to: 
 Options:  <1> Mn (IV). <2> Mn (VI) <3> Mn (VII). <4> Mn (V). <5> Mn (I).
