Final answer:
An autotroph, like an oak tree, can produce its own food via photosynthesis. Organisms like lions, mushrooms, and humans are heterotrophs and depend on others for food. The correct answer is C) Oak tree.
Step-by-step explanation:
An autotroph is an organism that can produce its own food using sunlight and carbon from carbon dioxide to synthesize chemical energy in the form of carbohydrates. This process is known as photosynthesis, and it's carried out by photoautotrophs which include plants, algae, and certain bacteria such as cyanobacteria. These organisms are vital to ecosystems as they are the producers, supplying energy for other living beings.
Given the options A) Lion, B) Mushroom, C) Oak tree, D) Human, the example of an autotroph is C) Oak tree. Lions are carnivores, mushrooms are decomposers, humans are omnivores, and all three are considered heterotrophs because they cannot produce their own food and must rely on other organisms for energy.