The H₂PO₄^- Ion Has Both a Conjugate Acid and a Conjugate

The H₂PO₄^- ion has both a conjugate acid and a conjugate base. It is true that

A) H₃PO₄ is the conjugate acid.
B) HPO₄^2- is the conjugate base.
C) H₂PO₃^- is the conjugate base.
D) More than one correct response.
E) No correct response.