Portion of the marine biome shallow enough for sunlight to penetrate:

• A. Aphotic zone
• B. Photic zone
• C. Benthic zone
• D. Limnetic zone

Answer: (B)

The main idea here is the light-driven zone in the ocean. The portion of the marine environment that receives enough sunlight for photosynthesis is the photic zone. Sunlight in this layer supports phytoplankton and other photosynthetic organisms, which form the base of the marine food web. In clear water, this sunlit layer can extend down to about 200 meters, but depth varies with water clarity. Below this depth, light is too weak for photosynthesis, marking the aphotic zone. The benthic zone refers to the ocean floor, and the limnetic zone is a freshwater term for open water in lakes, not a marine concept. So the sunlit marine zone where photosynthesis can occur is the photic zone.