The conjugate acid of \[HPO_{4}^{2-}\]is [MP PMT 1987, 90, 91; EAMCET 1993]

• A. \[{{H}_{2}}PO_{4}^{-}\]
• B. \[PO_{4}^{3-}\]
• C. \[{{H}_{3}}P{{O}_{4}}\]
• D. \[{{H}_{3}}P{{O}_{3}}\]