Final answer:
Autotrophs are organisms that produce their own food, and an example of an autotroph is phytoplankton.
Step-by-step explanation:
Autotrophs are organisms that can produce their own food using energy from sunlight or inorganic substances. These include plants, algae, and some bacteria. Out of the given options, phytoplankton is an example of an autotroph as it uses sunlight and nutrients to carry out photosynthesis and produce food.
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