Gas is escaping from a spherical balloon at a constant rate of 2 fˆ3/min. How fast is the outer surface area shrinking?

Problem
Gas is escaping from a spherical balloon at a constant rate of 2 ft3/min. How fast, in ft2/min, is the outer surface area of the balloon shrinking when the radius is 12 ft?

A.   1/2 C.   1/3
B.   1/5 D.   1/4