The radius of a cylinder is increasing at the rate of 3 cm/sec and its height is decreasing at the rate of 4 cm/sec. Find the rate of change of its volume when the radius is 4 cm and height is 6 cm.
a) -60π cm³/sec
b) -48π cm³/sec
c) -36π cm³/sec
d) -24π cm³/sec
