Which of the following is not released during decay of living matter?

Oxygen is not released during decay of living matter. During the process of decay, microorganisms break down complex organic compounds into simpler substances. In the absence of oxygen, this process is called anaerobic decay, and the end products include methane and carbon dioxide. In the presence of oxygen, the process is called aerobic decay, and the end products include carbon dioxide, water, and heat energy. However, oxygen itself is not released during the decay process.