Chlorobenzene reacts with $\mathrm{Mg}$ in dry ether to give a compound (A) which further reacts with ethanol to yield

The reaction can be represented as below.

${\mathrm{C}}_6{\mathrm{H}}_5-\mathrm{Cl}+\mathrm{Mg}\stackrel{\mathrm{dry} \mathrm{ether}}{\to }{\mathrm{C}}_6{\mathrm{H}}_5-\mathrm{MgCl}\stackrel{{\mathrm{C}}_2{\mathrm{H}}_5\mathrm{OH}}{\to }{\mathrm{C}}_6{\mathrm{H}}_6$

The final product obtained is benzene.

Hence, the correct answer is option (D) Benzene