Which of the following esters, when treated with one equivalent of $\mathrm{NaOEt}$ in ethanol followed by acidification, give a self-condensation (Claisen) product in good yield? (The overall reaction is driven by deprotonation of the beta-keto ester product.)

A Claisen condensation needs an ester with alpha hydrogen, and the beta-keto ester product must retain an acidic hydrogen between the two carbonyls so that the final deprotonation drives the equilibrium. Ethyl ethanoate and ethyl propanoate both give such products. Ethyl 2-methylpropanoate gives a product whose central carbon is quaternary (no acidic H), and ethyl benzoate has no alpha H at all.