Pick out incorrect statement

A. The pH at which Anion = Cation is called isoelectric point. At isoelectric point, $\mathrm{\alpha }$ -amino acids do not migrate when electric field is applied.

B. $-\mathrm{S}{\mathrm{O}}_3\mathrm{H}$ is strongly acidic and donates ${\mathrm{H}}^{+}$ to weakly basic arylamino group. ArCOOH is not acidic enough to transfer ${\mathrm{H}}^{+}$ to the arylamino group.

C. In $\mathrm{p}-{\mathrm{H}}_3\stackrel{+}{\mathrm{N}}{\mathrm{C}}_6{\mathrm{H}}_4\mathrm{S}{\mathrm{O}}_3,{\mathrm{H}}_3\stackrel{+}{\mathrm{N}}$ is acid enough to transfer ${\mathrm{H}}^{+}$ to bases to give the soluble anion, $\mathrm{p}-{\mathrm{H}}_2\mathrm{N}-{\mathrm{C}}_6{\mathrm{H}}_4\mathrm{S}{\mathrm{O}}_3.-\mathrm{S}{\mathrm{O}}_3$ is too feebly basic and cannot accept ${\mathrm{H}}^{+}$ from acids.

D. $\mathrm{\alpha }\text{-}{\text{H}}_3\stackrel{+}{\mathrm{N}}$ group increases acidity, because of its electron-withdrawing inductive effect.