The role of chlorophyll in photosynthesis is primarily to C. Absorb light energy.
While chlorophyll is involved in the process of splitting water molecules (B) and facilitating electron transfer (A), its main function is to capture light energy from the sun, which is then used to drive the photosynthetic reactions. Therefore, while chlorophyll contributes to the other processes, its primary role is absorption of light energy.
If you were considering a broader perspective where chlorophyll's involvement in all these processes is acknowledged, the answer could also be seen as D. All of the above. However, in a strict sense focused solely on its key function, C is the most accurate choice.