Which is a biotic factor operating within an ecosystem?
A. the amount of helium gas in the air.
B. the rate of flow of water in a river.
C. the type of climate in a given region.
D. the carnivores that consume other animals.
Biotic means living. The only living factor of the choices given is the carnivore. Abiotic factors, or nonliving factors, are represented by the other choices.