A.
c ( H + )+ c ( H 2 PO 4 - )+ 2 c ( H 3 PO 4 )= c ( OH - ) + c ( PO 4 3 - )
B.
c ( H + )+ c ( H 2 PO 4 - )+ c ( H 3 PO 4 )= c ( OH - ) + c ( PO 4 3 - )
C.
c ( H + )+ c ( H 2 PO 4 - )+ c ( H 3 PO 4 )= c ( OH - ) + 2 c ( PO 4 3 - )
D.
c ( H + )+ c ( H 2 PO 4 - ) = c ( OH - ) + c ( PO 4 3 - )