The compound from the following with highest  pka is

All aromatic acids are more acidic than aliphatic acids except HCOOH.In C6H5–COOH,  –C6H5 group show +M effect and –I effect due to sp2 hybridized carbon atoms of benzene ring.– I effect is  due to sp2 carbons –I effect in this compound dominates +M effect.∴Benzoic acid is more acidic than all aliphatic acids except HCOOH∴HCOOH > C6H5COOH > CH3COOHComparing C6H5COOH, C6H5CH2COOH, CH3COOHC6H5COOH > C6H5CH2COOH > CH3COOH∴HCOOH > C6H5COOH > C6H5CH2COOH  > CH3COOHpka of HCOOH < C6H5COOH < C6H5CH2COOH