B. Scarcity of drinking water
Answer:
Moon, planet, planet
Explanation:
Moons revolve around planets, Jupiter is considered a planet because it revolves around the sun, and a planet is a body that revolves a star.
It is important to understand because it's the way all cells reproduce (except sperm and egg cells, they do meiosis), and our cells are the essential parts of our whole being.
D) Natural Gas i think is correct sorry if im wrong