Which category relates to organisms that obtain energy from chemical compounds?

The correct choice pertains to organisms that derive energy from the chemical compounds present in their environment. Chemoheterotrophs are specifically defined by their dual reliance on obtaining both their energy and carbon from organic molecules. This category includes a wide range of organisms, including many bacteria, fungi, and animals, that consume organic material as a source of both energy and carbon.

In this context, energy is gained through metabolic reactions that break down these organic compounds, which can range from carbohydrates to proteins. This mode of obtaining energy is essential for organisms that cannot produce their own food or fix carbon dioxide.

The distinction of chemoheterotrophs is crucial in understanding microbial ecology and nutrient cycling, as they play vital roles in decomposing organic matter and recycling nutrients back into the ecosystem.