Answer:
Radiant energy
Step-by-step explanation:
Plants have green pigments called chlorophyll in the chloroplasts of their cells. Chlorophyll and other photosynthetic pigments trap the radiant energy of sun. The absorbed radiant energy is stored into ATP and NADPH during light reactions of photosynthesis. The light-independent phase of photosynthesis uses ATP as a source of energy to drive the energy-requiring chemical reactions which in turn fix the atmospheric CO2 into carbohydrates such as glucose. NADPH serves as a reducing power during this phase.
Therefore, plants transform the radiant energy of the sun into the chemical energy of carbohydrates by the process of photosynthesis.