Final answer:
Autotrophs derive organic carbon by fixing carbon from CO2, a process central to the carbon cycle. They convert CO2 into essential organic compounds, such as glucose, which are crucial for their energy storage and growth. The option (A) is correct.
Step-by-step explanation:
Autotrophs primarily derive their organic carbon by fixing carbon from CO2.
In the carbon cycle, while heterotrophs rely on organic molecules for carbon and energy, autotrophs use carbon fixation to convert inorganic carbon dioxide (CO2) into organic carbon compounds like glucose. This process is essential for the synthesis of carbohydrates that are vital for their growth and energy storage. Photoautotrophs, such as plants and certain bacteria, achieve this through photosynthesis, utilizing light energy, while chemoautotrophs use inorganic chemical compounds to drive the fixation process.
Autotrophic prokaryotes are examples of organisms that synthesize organic molecules from carbon dioxide. Versatile in their metabolism, autotrophs can either be photoautotrophs, using sunlight, or chemoautotrophs, using chemical energy to produce organics. Therefore, option (A) is correct.