Which organisms are classified as autotrophs?

Autotrophs are organisms that can produce their own food through processes like photosynthesis or chemosynthesis. Plants are a prime example of autotrophs because they contain chlorophyll, allowing them to capture sunlight and convert carbon dioxide and water into glucose and oxygen. This ability to synthesize their own food is what categorizes them as primary producers in the ecosystem.

Coral reefs, while sometimes considered in connection with autotrophic processes due to their symbiotic relationships with algae, do not independently produce food and, therefore, are not classified as autotrophs. Fishes and marine mammals are heterotrophs because they obtain energy and nutrients by consuming other organisms, rather than producing their own food.

Thus, the correct option demonstrates a clear understanding of what defines autotrophic organisms in marine ecosystems.