which list of factors best support the concept that they are "just right" for the planet earth to support life?
It would be C. Gravity is pretty self explanatory, it holds the earth together and everything on it. Atmosphere because it has the ozone layer to protect us from UV rays, it has the right amount of oxygen and other elements to allow us to breathe, and it regulates the temperature. Water because it provides life. Self explanatory. Plants because they help create oxygen and they feed us and other things we eat.