When Phosphoric Acid (H₃PO₄)dissolves in Water,the Following Equilibrium Is Established

When phosphoric acid (H₃PO₄) dissolves in water,the following equilibrium is established: H₃PO₄ + H₂O H₃O⁺ + H₂PO₄^- If K_a = 7.5 × 10^-3 for H₃PO₄,which statement concerning an aqueous solution of phosphoric acid is correct?

A) An aqueous solution of phosphoric acid contains mainly H₃PO₄ molecules.
B) An aqueous solution of phosphoric acid contains predominantly H₃O⁺ and H₂PO₄^- ions.
C) An aqueous solution of phosphoric acid contains equal amounts of H₃O⁺ and H₃PO₄.
D) An aqueous solution of phosphoric acid contains a greater concentration of dissolved ions than it does neutral phosphoric acid molecules.