A spherical snowball is melting in such a manner that its radius is changing at a constant rate, decreasing from 36 cm to 9 cm in 30 minutes. At what rate, in cubic cm per minute, is the volume of the snowball changing at the instant the radius is 5 cm?

a) 675π
b) −90π
c) −80π
d) −180π
e) 45π