A right circular cylinder has volume V=πr2h, where r is its radius and h its height, both measured in centimeters. At a certain instant the radius is 10 cm and increasing at 0.3 cm/min, while the height is 25 cm and decreasing at 0.5 cm/min. Which of the following statements about dtdV at that instant is correct?
a) 25π cm3/min
b) 0
c) 100π cm3/min
d) −50π cm3/min