What is the process called by which plants make their food?

Photosynthesis is the process by which plants make their food, using sunlight, carbon dioxide, and water. During this process, plants convert light energy into chemical energy, storing it in the form of glucose. Chlorophyll, the green pigment in plants, plays a crucial role by capturing sunlight during the day. This process takes place primarily in the leaves where chloroplasts are located.

Plants utilize the glucose produced through photosynthesis not only as a food source for energy but also as a building block for growing and developing. The oxygen released as a byproduct of photosynthesis is essential for the survival of most living organisms, as it contributes to the atmosphere we breathe.

The other processes mentioned in the options serve different purposes. Fermentation is a method used by some organisms to convert sugars into energy without oxygen, typically in the absence of light. Respiration is a metabolic process where glucose is broken down to release energy for cellular activities, which occurs in both plants and animals. Digestion refers to the breakdown of food into smaller components for absorption, a process that does not apply to how plants create energy. Thus, photosynthesis is the correct answer as it specifically identifies the unique way in which plants produce their own food.