Oxidation number of P in $PO_{4}^{3-}$, of S in $SO_{4}^{2-}$and that of Cr in $Cr_{2}O_{7}^{2-}$ are respectively :

Question

( A ) +3, +6 and +5
( B ) +5, +3 and +6
( C ) +3, +6 and +6
( D ) +5, +6 and +6