Final answer:
Among the given options, sulfur is the least abundant element in living organisms, as oxygen, carbon, and nitrogen are among the four most common elements that make up about 96% of living cells.
Step-by-step explanation:
The least abundant element in living organisms among the options provided is sulfur. Oxygen, carbon, and nitrogen are part of the four most common elements found in living organisms, which also includes hydrogen. Collectively, these four elements constitute about 96% of the mass of most cells. Sulfur, while vital for the structure of proteins and certain metabolic processes, is found in much smaller quantities compared to the other elements mentioned.
Abundance of Elements in Cells
In living cells, hydrogen is the most abundant element, followed by oxygen, carbon, and nitrogen. Sulfur is present as well, but to a far lesser extent, and is considered a macronutrient in biological contexts. Unlike the elements of carbon, oxygen, and nitrogen which are central to the structure and function of nucleic acids, proteins, carbohydrates, and lipids, sulfur plays a more specific role, for instance, in amino acids like cysteine and methionine, as well as certain vitamins and cofactors.