Which type of molecules contain carbon and are only produced by living organisms?

Organic molecules are defined as those that contain carbon and are specifically produced by living organisms. This distinction is fundamental in biology and chemistry; organic molecules typically include a broad range of compounds such as carbohydrates, lipids, proteins, and nucleic acids. The presence of carbon is a key characteristic that differentiates these molecules from inorganic ones, which do not necessarily contain carbon and can be found in non-biological contexts, such as minerals and water.

While macromolecules and simple sugars are indeed types of organic molecules, the term "organic molecules" encompasses a wider variety of compounds. Thus, stating that organic molecules are exclusively produced by living organisms aligns perfectly with the definition of organic chemistry, making this the most appropriate choice among the options provided.