Concept:Animals release carbon dioxide into the atmosphere through two main processes: respiration and the decay of dead organic matter.Explanation:During respiration, animals break down glucose to obtain energy, producing carbon dioxide as a waste product.After death, decomposers act on animal bodies and organic wastes, breaking them down and releasing trapped carbon as carbon dioxide.Ammonification releases ammonia, not carbon dioxide, so it is not involved in this carbon release.Answer:A. respiration and decay