Which of the reactions of photosynthesis require pigments absorbing solar energy?

During photosynthesis, a green pigment called chlorophyll is required to absorb solar energy. The reaction in photosynthesis that requires pigments to absorb solar energy is called LIGHT REACTION.

Explanation:

Light reaction is considered to be the first stage or phase during photosynthesis and the key elements that is needed for the reaction to take place is- sunlight and chlorophyll.  Chlorophyll is a pigment that makes the leaves of the plant appear green. There is also another important function of chlorophyll that is to trap solar energy during the process of photosynthesis to convert the trapped solar energy into chemical energy- ATP molecules. These ATP molecules then form glucose- food for the plant.

substitution is the answer in this case