Consider a Buffer Solution Made Up of H₂PO₄^- and HPO₄^2-

Consider a buffer solution made up of H₂PO₄^- and HPO₄^2- For H₂PO₄^-, K_a = 6.2 × 10^-8. What mole ratio of HPO₄^2- to H₂PO₄^- will give a pH of 7.35?

A) 0.14 to 1
B) 0.72 to 1
C) 1 to 1
D) 1.4 to 1
E) More information is needed to answer this question.