$Y =3 K (1-\sigma)$
$\Rightarrow 2 \eta(1+\sigma)=3 K (1-2 \sigma)$
$\Rightarrow \sigma=\left(\frac{3 K -2 \eta}{6 K +2 \eta}\right)$
$(I)$ the loss of gravitational potential energy of mass $M$ is $Mgl$
$(II)$ the elastic potential energy stored in the wire is $Mgl$
$(III)$ the elastic potential energy stored in wire is $\frac{1}{2}\, Mg l$
$(IV)$ heat produced is $\frac{1}{2}\, Mg l$
Correct statement are :-