What is the basicity of $H_3PO_4$?

(3) The structure of $H_3PO_4$ (orthophosphoric acid) shows that it contains three $P-OH$ groups.
The basicity of an oxoacid is defined by the number of ionizable $H$ atoms attached to oxygen atoms.
Since there are three $OH$ groups present in $H_3PO_4$,it can release three $H^+$ ions in an aqueous solution.
Therefore,its basicity is $3$,and it is a tribasic acid.