Explanation

(b) The volume of liquid displaced by floating ice $V_{D} = \frac{M}{\sigma_{L}}$
Volume of water formed by melting ice, $V_{F} = \frac{M}{\sigma_{W}}$
If $\sigma_{L} > \sigma_{W}$, then $\frac{M}{\sigma_{L}} < \frac{M}{\sigma_{W}}\ i.e.\ V_{D} < V_{F}$
$i.e.$ volume of liquid displaced by floating ice will be lesser than water formed and so the level if liquid will rise