Fact 1: Cell division often causes growth. Fact 2: Cell division is relatively slow and requires a lot of energy. Given the two facts above, what often requires a lot of energy?

Select from:
(a). pigeons
(b). monkeys
(c). horizon
(d). growth
(e). humans
(f). omnivores
(g). waiting
(h). distance
The answer is:
(d).