Which process occurs in the mitochondria of both plants and animals?

Cellular respiration is the process that occurs in the mitochondria of both plants and animals, which is why this choice is correct. This process involves breaking down glucose and other organic molecules to produce adenosine triphosphate (ATP), a usable form of energy for the cell. During cellular respiration, oxygen is consumed, and carbon dioxide and water are produced as byproducts.

In both plants and animals, mitochondria serve as the site for this critical energy metabolism. While plants also have chloroplasts for photosynthesis, cellular respiration is a universal process necessary for energy production in all eukaryotic cells. This is crucial for biological functions, growth, and maintenance. This differentiates it from the processes of photosynthesis, which occurs only in plants and some other organisms, and fermentation, which is an anaerobic process that occurs in the absence of oxygen and is not limited to mitochondria.