Ethanol on reaction with alkaline ${\mathrm{KMnO}}_4$ gives:

Products obtained in the above reaction are:

Complete the following:

$\left(\mathrm{a}\right)$ 

$\left(\mathrm{b}\right)$ 

$\left(\mathrm{c}\right)$ 

In the reaction sequence:

$\mathrm{A}, \mathrm{B}, \mathrm{C}$ and $\mathrm{D}$ are given by the set.