What distinguishes autotrophs from heterotrophs?

Autotrophs are organisms that can produce their own food through processes like photosynthesis or chemosynthesis. This ability allows them to convert inorganic substances into organic compounds that serve as energy sources. For instance, plants absorb sunlight and use it to convert carbon dioxide and water into glucose, which they then use for metabolic processes.

On the other hand, heterotrophs cannot synthesize their own food and instead rely on consuming other organisms, whether they be plants, animals, or decomposed organic matter, to obtain energy and nutrients. This distinction is fundamental in ecology and biology, as it highlights the different roles these groups play in food webs and ecosystems.

The other options do not accurately capture the essential difference between these two groups. Autotrophs and heterotrophs can vary significantly in size, and energy requirements depend on many factors beyond just their classification. Therefore, the correct choice accurately reflects the fundamental relationship between how these two types of organisms acquire energy.