What is the difference between an autotroph and a heterotroph?

The correct answer highlights the fundamental distinction between autotrophs and heterotrophs based on how they obtain energy and organic compounds. Autotrophs are organisms that can produce their own food from inorganic substances. They typically use processes like photosynthesis, where they convert sunlight into chemical energy, or chemosynthesis, where they derive energy from inorganic chemical reactions. This capability allows them to harness energy from their surroundings and synthesize organic molecules necessary for growth and maintenance.

In contrast, heterotrophs cannot produce their own food and must obtain organic matter from other organisms. They rely on consuming plants, animals, or decomposing organic material for energy and nutrients. This systematic relationship is vital for ecosystems, as autotrophs form the base of the food web, providing energy for heterotrophs, which are necessary for recycling nutrients.

Thus, the correct answer accurately reflects the roles of autotrophs and heterotrophs in ecological systems and their methods of obtaining energy.