A sphere of solid material of density d has a concentric spherical cavity of radius r. lf it just floats in water, i-e-, with its upper surface touching the water surface, then R and r ate related as: (Take density of water = 1)

• A

  ${\mathrm{r}}^3={\mathrm{R}}^3\left(1-\frac{1}{\mathrm{d}}\right)$

• B

  ${\mathrm{r}}^3={\mathrm{R}}^3(\mathrm{d}-1)$

• C

  ${\mathrm{r}}^3={\mathrm{R}}^3\left(1+\frac{1}{\mathrm{d}}\right)$

• D

  ${\mathrm{r}}^3=\frac{{\mathrm{R}}^3}{\left(1+{\displaystyle \frac{1}{\mathrm{d}}}\right)}$