The burial practices of humans have not led to any significant changes in Earth's biome. Matter can not be created nor destroyed. Burial practices lead to burying the dead bodies into the Earth, where they are decayed by the action of several microbes and insects. The organic and inorganic compounds are added to the Earth.
D. Gravity and Distance. The distance earth is from the sun is what's keeping us from barreling into the mass of flame and heat. The distance between us and the moon is what keeps the moon from crashing into us. It could not be C, as the definition of inertia is: "a property of matter by which it continues in its existing state of rest or uniform motion in a straight line, unless that state is changed by an external force." Hope this helps :)