Metamers are isomers with distinct alkyl groups on two sides of functional groups but the same molecular formula.${\mathrm{C}}_2{\mathrm{H}}_5-\mathrm{O}-{\mathrm{C}}_2{\mathrm{H}}_5 \mathrm{and} {\mathrm{CH}}_3-\mathrm{O}-{\mathrm{C}}_3{\mathrm{H}}_7$

In contrast to n-propyl methyl ether, which contains one methyl and one propyl on either side, diethyl ether is symmetric and has two carbons on both sides. Both are hence metamers.

Hence, correct option is: (A) Metamers