Explain why both the ovarian cycle and uterine cycle are necessary for fertilization to occur? Please help me

Alright! 1. the carbon that is found in the trees or plants are eaten by animals that are vegetarians or omnivores(eat plants and meat).2. the animal might excread the waste(basically whatever the body did not need)with can then decompose and make the soil have carbon.  3. the animal also can breath in the carbon that is found in the air.  4. the carbon molecule can also be released by chemical reaction like the fire in the picture.  5. carbon can also be found in bodies of water.  hope this ! : )

Periods of the paleozoic eracambrian period.ordovician period.silurian period.devonian period.carboniferous period.permian period.