Endocrine and circulatory (C) Endocrine system consists of glands and the hormones they secrete whist the circulatory system is the blood or as I like to call the “transport system” of the body.
Answer: The answer is B
Explanation: It’s P2O3 and P4 and O3, to balance them you have to put a 2 in the first so it’ll be P4O6 ——— P4 , O6.
D. Predators
Predators keep populations of other species in check. This was pretty clearly demonstrated in Yellowstone National Park after the wolves were eradicated there. The deer populations increased to the point that the aspen trees nearly disappeared due to the saplings' being eaten by deer. Since the reintroduction of wolves to the park, the aspen trees have begun to flourish once again.