Alkaline hydrolysis of esters (saponification) is a nucleophilic acyl substitution reaction where a nucleophile ($OH^-$) attacks the electrophilic carbonyl carbon.

1. Electronic Effect: The presence of Electron-Withdrawing Groups (EWG) (such as $-NO_2$, $-Cl$, or halogen atoms) on the ester molecule withdraws electron density from the carbonyl carbon. This increases the positive charge on the carbon, making it more susceptible to nucleophilic attack by $OH^-$, thus increasing the rate of hydrolysis.
2. Steric Effect: Bulky groups near the carbonyl carbon hinder the approach of the nucleophile, decreasing the rate.

Therefore, the ester with the strongest electron-withdrawing substituent (and least steric hindrance) will hydrolyze most easily.