Explanation:

- Autotrophic organisms, like green plants, make their own food.

- Their carbon and energy needs are met by converting sunlight, water, and carbon dioxide into glucose.

- Option 1: Glycogenation—This is not a real term or relevant process for autotrophs. Glycogen is how animals store energy.

- Option 2: Locomotion—This is movement and not related to carbon or energy capture.

- Option 3: Photosynthesis —This is the correct answer. It's how autotrophs capture energy from sunlight and carbon from CO2.

- Option 4: Respiration—This is how organisms use energy, not obtain it.