Answer:
Option C
Explanation:
Bulk modulus.
$K= \frac{Volumetric stress}{Volumetric strain}$
$=\frac{\frac{\triangle p}{V}}{V}$
$K=\frac{mg}{a(\frac{3\triangle r}{r})}$
$v=\frac{4}{3}\pi^{3}$
$\frac{\triangle V}{V}=\frac{3\triangle r}{r}$
$\frac{\triangle r}{r}=\frac{mg}{3Ka}$