Correct option (d) Williamson's synthesis
Explanation:
$$
\begin{aligned}
\mathrm{C}_{2} \mathrm{H}_{5}-\mathrm{Cl}+& \mathrm{Na}-\mathrm{O}-\mathrm{C}_{2} \mathrm{H}_{5} \rightarrow \\
\mathrm{C}_{2} \mathrm{H}_{5}-\mathrm{O}-\mathrm{C}_{2} \mathrm{H}_{5}+\mathrm{NaCl}
\end{aligned}
$$
The above reaction is called as Williamson's synthesis.