Which component contains carbon, hydrogen, oxygen and nitrogen atoms and is used by living organisms?

• A. Inorganic minerals
• B. Water
• C. Energy
• D. Organic nutrients

Answer: (D)

Living organisms rely on organic nutrients—carbon-based molecules that provide the carbon skeletons and diverse functionalities they need for energy, growth, and maintenance. These compounds typically contain carbon, hydrogen, and oxygen, and many also include nitrogen, forming the building blocks of carbohydrates, fats, proteins, and nucleic acids. This is why organic nutrients are the main source of the carbon-containing molecules that underpin metabolism and structure. Inorganic minerals lack carbon-hydrogen bonds and mainly supply minerals we need for function. Water is essential and contains hydrogen and oxygen but does not supply carbon-containing molecular frameworks. Energy is a property of the system, not a molecule that contains atoms. So the option that fits best is organic nutrients.