Which of the following elements is essential for all living organisms?

Carbon is essential for all living organisms because it serves as the fundamental building block of life. All organic molecules, which include carbohydrates, proteins, lipids, and nucleic acids, contain carbon atoms. This unique ability of carbon to form stable bonds with many elements, including itself, allows for the creation of complex and diverse molecular structures necessary for biological functions.

In addition to its role in forming organic compounds, carbon is involved in various metabolic processes and is a key participant in the biological carbon cycle. Organisms utilize carbon dioxide during photosynthesis, and carbon compounds are central to the energy transfer processes during cellular respiration. Overall, carbon's versatility and presence in biological macromolecules make it indispensable for life.