Which of the following describes organic molecules?

The correct choice identifies organic molecules as those consisting primarily of carbon and hydrogen atoms. Organic chemistry is fundamentally centered around carbon, and the presence of carbon in a molecule is what typically classifies it as organic. These carbon and hydrogen atoms can form various structures, including chains and rings, allowing for an immense variety of organic compounds, such as carbohydrates, lipids, proteins, and nucleic acids.

The distinction of organic molecules is significant; the variety of functional groups that can be attached to the carbon backbone further contributes to the diverse chemical properties and reactions of organic compounds. Understanding that carbon’s ability to form four covalent bonds allows it to create stable bonds with other elements, especially hydrogen, is key to grasping the definition of organic molecules in biological contexts.

In contrast to the correct option, the other choices either describe characteristics that do not align with the fundamental definition of organic molecules, such as including metals or being defined by the absence of carbon. These aspects are pertinent to different categories of chemistry, but they do not apply when identifying organic molecules.