A dilute ferrous sulphate solution was gradually added to the beaker containing acidified permanganate solution. The light purple colour of the solution fades and finally disappears. Which of the following is the correct explanation for the observation?<br><br><b>(a)</b> KMnO<sub>4</sub> is an oxidising agent, it oxidises FeSO<sub>4</sub>.<br><b>(b) </b>FeSO<sub>4</sub> acts as an oxidising agent and oxidises KMNO<sub>4</sub>.<br><b>(c) </b>The colour disappears due to dilution; no reaction is involved.<br><b>(d) </b>KMnO<sub>4</sub> is an unstable compound and de-composes in presence of FeSO<sub>4 </sub>to a colourless compound.