Question

Carbon is the basis of all life and is constantly being cycled through ecosystems. In which form is carbon passed along from plants to animals?

Answer 1

Plants gain carbon through photosynthesis, and then animals will eat those plants and gain some of the carbon that was made by the plant. If the animal does not eat plants, then they obtain it through eating other animals who ate plants.
Is this what you were looking for? Your question was a little confusing.

Answer 2

Carbon is passed from plants to animals in the plant tissue. Plants take carbon dioxide and water and with energy from the sun, they build sugars and other biomolecules. So animals get sugars and other carbohydrates, proteins and fats from the plants they eat. All of those are carbon based molecules. The question is most likely looking for sugar or carbohydrates, but really it is all three of those major groups, carbos, proteins and fats.