Which of the following oxyacids does not contain a $P-O-P$ bond?

Given below are two statements:
Statement $I$: The $N-N$ single bond is weaker and longer than the $P-P$ single bond.
Statement $II$: Compounds of group $15$ elements in $+3$ oxidation state readily undergo disproportionation reactions.
In the light of the above statements,choose the correct answer from the options given below:

Ionic radius (in $\mathring{A}$) of $As^{3+}$,$Sb^{3+}$ and $Bi^{3+}$ follow the order:

The number$(s)$ of $-OH$ group$(s)$ present in $H_3PO_3$ and $H_3PO_4$ is/are

For the properties mentioned,the correct trend for the different species is in

Strong reducing behaviour of $H_3PO_2$ is due to