The acid with highest Pka value is

Ka ∝ Acidic strength , thus lesser Ka and higher Pka means lesser acidic strength ;-CH3 at meta position . . . +I effect . . .EDG -OCH3 at para position . . .-I, +M (-I < +M) . . .EDG-NO2 at para posotion. . .-I, -M . . .EWGElectron donating power of -OCH3 > -CH3 EDG decrease acidic strength;EWG increase acidic strength ;