The correct option is A Pyrophosphoric acid
The oxidation state of phosphorus in pyrophosphoric acid (H4P2O7) is +5. The oxidation state of phosphorus in hypophosphorus acid (H3PO2) is +1, in orthophosphorous acid (H3PO3) it is +3 and in hypophosphoric acid (H4P2O6) it is +4.