The correct answer is Option (3) – Photosynthesis

Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy, usually from the sun, into chemical energy stored in glucose or other organic molecules. During photosynthesis, plants use carbon dioxide and water, along with light energy absorbed by chlorophyll pigments in chloroplasts, to produce glucose and oxygen. This glucose serves as the primary energy source for the plant, while the oxygen is released into the atmosphere as a byproduct. Therefore, photosynthesis is the process by which plants synthesize their own food.