What differentiates autotrophs from heterotrophs?

Autotrophs are organisms that can produce their own food through processes such as photosynthesis or chemosynthesis. This ability allows them to convert inorganic substances (like carbon dioxide and water) into organic compounds (like glucose) using an energy source (like sunlight or chemical reactions). This characteristic is fundamental in ecological systems as it forms the base of food chains and provides energy and nutrients for heterotrophs, which rely on other organisms for their energy and nutrient needs.

The other options do not accurately define the distinction between autotrophs and heterotrophs. For instance, not all heterotrophs recycle nutrients in the same manner, nor are all heterotrophs herbivores; many are carnivores or omnivores. The size of organisms is not a defining factor, as both autotrophs and heterotrophs can vary widely in size. Thus, the correct answer highlights the primary functional role that autotrophs play in ecosystems by producing their own food, sustaining themselves and other life forms.