Which of the following elements constitutes approximately 96% of living matter?

Living matter is primarily composed of a small number of elements that are essential for life. Among these elements, carbon is a fundamental building block. It plays a crucial role in forming the complex molecules necessary for all biological processes, such as proteins, nucleic acids, carbohydrates, and lipids. The ability of carbon to form four covalent bonds allows for the creation of diverse organic compounds, which are essential for the structure and function of living organisms.

In terms of abundance, approximately 96% of living matter is made up of four key elements: carbon, hydrogen, oxygen, and nitrogen. Within this grouping, carbon is particularly significant due to its central role in biochemical frameworks. Other elements, such as calcium, phosphorus, and sodium, while also important to biological systems, do not make up the majority composition of living matter when considering the overarching molecular structures and functions. Thus, carbon's prevalence and versatility in forming essential biomolecules account for its designation as constituting a major portion of the composition of living organisms.