Which of the following reagents, on reaction with ethyl bromide, would yield diethyl ether as the major product?

Diethyl ether is obtained from ethyl bromide by treating it with sodium ethoxide and the name of the reaction is williamson's synthesis.

$\underset{\mathrm{Sodiium} \mathrm{ethoxide}}{{\mathrm{CH}}_2{\mathrm{CH}}_3-\mathrm{ONa}}+\underset{\mathrm{Ethyl} \mathrm{bromide}}{\mathrm{Br}-{\mathrm{CH}}_2{\mathrm{CH}}_3}\stackrel{\mathrm{\Delta }}{\to } {\mathrm{CH}}_3-\mathrm{O}-{\mathrm{CH}}_3+\mathrm{NaI}$

Diethyl ether is also obtained, When ethyl bromide is treated with dry silver oxide

$\underset{\mathrm{ethylbromide}}{2{\mathrm{CH}}_3{\mathrm{CH}}_2\mathrm{Br} }+\underset{\mathrm{drysilveroxide}}{ {\mathrm{Ag}}_2\mathrm{O}}\to {\mathrm{CH}}_3{\mathrm{CH}}_2{\mathrm{OCH}}_2{\mathrm{CH}}_3+\underset{ \mathrm{silverbromide}}{2\mathrm{AgBr}}$