Question

what best describes the association between the carbon cycle, plants, and animals?
plants fix carbon and release oxygen, and animals release carbon and use oxygen.
animals fix carbon and release oxygen, and plants release carbon and use oxygen.
animals fix carbon through respiration, and plants fix carbon through photosynthesis.
plants decompose fixing carbon, and animals decompose releasing carbon.

Explanation:

Plants perform photosynthesis, which fixes carbon dioxide ($CO_2$) and releases oxygen ($O_2$). Animals perform respiration, which uses $O_2$ and releases $CO_2$.

Answer:

Plants fix carbon and release oxygen, and animals release carbon and use oxygen.