Radius of a spherical balloon is increasing at the rate of 0.5 cm/sec; then the rate of increase of its volume when radius is 10 cm is

$150 \pi cm^3 / sec$ $200 \pi cm^3 / sec$ $400 \pi cm^3 / sec$ $300 \pi cm^3 / sec$

$200 \pi cm^3 / sec$

The correct answer is Option (2) → $200 \pi cm^3 / sec$