Carbon and energy requirements of an autotrophic organism are fulfilled by ______.

photosynthesis

The correct answer is Option (3) -photosynthesis

Photosynthesis is the process by which autotrophic organisms, such as plants, algae, and some bacteria, convert carbon dioxide and water into organic compounds, particularly glucose, using light energy from the sun. This process occurs primarily in the chloroplasts of plant cells, where chlorophyll, the green pigment responsible for capturing light energy, is located.

During photosynthesis, light energy is absorbed by chlorophyll molecules in the chloroplasts. This energy is used to power a series of chemical reactions that result in the conversion of carbon dioxide (CO₂) from the atmosphere and water (H₂O) from the soil into carbohydrates, such as glucose (C₆H₁₂O₆). Oxygen (O₂) is also produced as a byproduct of this reaction, which is released into the atmosphere.

In summary, photosynthesis is the fundamental process by which autotrophic organisms obtain the carbon and energy they need to survive, and it plays a crucial role in the Earth's ecosystems by providing energy and organic matter for heterotrophicorganisms and sustaining life on the planet.