Given pKa values: o-nitrobenzoic acid 2.17, m-nitrobenzoic acid 3.45, p-nitrobenzoic acid 3.44, benzoic acid 4.20. The ortho isomer is far stronger than the meta and para isomers mainly because

1. Athe $-I$ effect acts at the shortest distance and the ortho substituent also forces $\mathrm{COOH}$ out of the plane of the ring (ortho effect)
2. Bthe $\mathrm{COOH}$ group is a $+M$ group which is deactivated only in the ortho isomer
3. Cthe nitro group forms intermolecular hydrogen bonds that weaken the $\mathrm{O}-\mathrm{H}$ bond of every isomer equally
4. Dthe nitro group donates electrons by $+R$ effect only from the ortho position