Correct option is: B) \(\frac{r}{3}\)
Volume of sphere of radius r = \(\frac 43 \pi r^3\)
= \(\frac r3 \times 4 \pi r^2\)
= \(\frac r3 \times \) surface area of sphere
Hence, the volume of sphere of radius 'r' is obtained by multiplying its surface area by \(\frac r3 \)