Four benzoic acids are shown beside the options (the drawn compound is benzoic acid, pKa 4.20). Select ALL the structures that are stronger acids than the drawn compound.

p-Nitrobenzoic acid (3.44) is stronger by -I and -M. m-Chlorobenzoic acid (3.83) is stronger by -I. o-Toluic acid (3.91) is stronger through the ortho effect: the methyl group forces COOH out of the ring plane, so the +R-like conjugation of the ring with COOH is lost and the acid is strengthened. p-Toluic acid (4.34) is weaker because of +I and hyperconjugation.