Concept:Methyl orange is an acid-base indicator that shows different colors depending on whether the medium is acidic or alkaline.Explanation:In an acidic solution, methyl orange forms a structure that appears red or pink.When the solution becomes alkaline, the indicator changes into a different molecular form.This alkaline form of methyl orange gives a distinct yellow color.So, testing methyl orange with an alkaline solution will show a yellow color.Answer:A. yellow