Photosynthesis
Photosynthesis is the process by which green plants prepare their own food, using the energy from sunlight, carbon dioxide from air and water.
The process of photosynthesis involves the presence of sunlight, carbon dioxide and water.
All of these must be present in the plant for photosynthesis to occur. The absence of even one of these elements, will not allow photosynthesis to occur.
Sunlight is able to reach the plant and the green pigment (chlorophyll) of the plant traps it. The chlorophyll has a chloroplast which performs this function.
Sun is the primary source of the energy. The light energy from the sun is used by green plants to prepare their own food.