The true statement about oxo acids of phosphorus ${\mathrm{H}}_3{\mathrm{PO}}_2,{\mathrm{H}}_3{\mathrm{PO}}_3$ and ${\mathrm{H}}_3{\mathrm{PO}}_4$ is     

The order of their acidity is ${\mathrm{H}}_3{\mathrm{PO}}_4>{\mathrm{H}}_3{\mathrm{PO}}_3>{\mathrm{H}}_3{\mathrm{PO}}_2$

All of them are reducing in nature

All of them are tribasic acids

The geometry of phosphorus is tetrahedral in all the three