Answer: D. The epipelagic zone
Step-by-step explanation:
The zones of the open ocean are, going downwards:
Epi -> Meso -> Bathy -> Abysso -> Hado.
The benthic zone is just referring to the ocean floor, on both the oceanic and continental shelf, and technically is not a part of the "open ocean" (it does not refer to the water but to the floor itself).
So the zone nearest the top, the epipelagic zone, would receive the most sunlight.