What is the process by which living cells (plant or animal) take in oxygen and give carbon dioxide?

The correct choice is respiration, which is a vital biochemical process that involves living cells taking in oxygen and using it to convert glucose into energy. During this process, carbon dioxide is produced as a waste product, which is then expelled from the cells. This cellular respiration occurs in both plant and animal cells and is essential for the energy production required for various cellular functions and overall growth.

In contrast, photosynthesis relates primarily to plants, where they take in carbon dioxide and sunlight to produce glucose and oxygen, not the reverse process of oxygen intake for energy. Transpiration refers specifically to the process by which water evaporates from the leaves of plants, playing a key role in water and nutrient transport but not involving oxygen and carbon dioxide exchange in the same manner as respiration. Fermentation is an anaerobic process that also breaks down glucose but does so in the absence of oxygen, resulting in by-products like lactic acid or ethanol instead of carbon dioxide during aerobic respiration. Thus, respiration is specifically and correctly identified as the process where living cells intake oxygen and release carbon dioxide.