The answer is a. light energy to chemical energy.
In the photosynthesis, plants use light energy from the sun as an energy source. This light energy from the sun is converted into chemical energy stored in carbohydrates made from carbon dioxide and water. So, when light reaches a leaf of a plant, it passes through to chloroplasts. The chloroplasts are organelles inside the leaf and contain pigment chlorophyll. Light excites chlorophyll and a series of chemical reactions occur inside the chloroplasts. As the result, carbohydrates which serve as a food for the plants are synthesised.
