Waxes are the esters of

The ester of a fatty acid and an alcohol is wax.

One fatty acid and one fatty alcohol are combined to create wax esters. Alcohols contain a hydroxyl group $\left({\mathrm{HO}}^{-}\right)$. There is a carboxyl (COOH) group in organic acids. Esters are created by joining organic acids and alcohols. In wax esters, ester linkages are created when the carboxyl groups of the fatty acids and the hydroxyl groups of the fatty alcohols combine.

$\mathrm{RCOOH}+\mathrm{ROH}\to \mathrm{RCOOR}+{\mathrm{H}}_2\mathrm{O}$

So, waxes are esters of long-chain alcohols and long-chain fatty acids.

Hence, option D is correct.