Calculate the Ratio of the Molarities of HPO₄^2- and H₂PO₄^-

Calculate the ratio of the molarities of HPO₄^2- and H₂PO₄^- ions required to achieve buffering at pH = 7.00 .For H₃PO₄,PK_a1 = 2.12,PK_a2 = 7.21,And pK_a3 = 12.68.

A) 0.81
B) 1.23
C) 0.62
D) 0.21
E) 1.62