Which zone begins at about 1000 meters and extends to greater depths, where no sunlight penetrates?

• A. Splash Zone
• B. Intertidal Zone
• C. Aphotic Zone
• D. Subtidal Zone

Answer: (C)

Light fades with depth in the ocean, creating distinct vertical zones defined by how much sunlight reaches them. The deep, dark zone begins around 1,000 meters and extends to the deepest parts, where no sunlight penetrates—the aphotic zone. In this region, photosynthesis isn’t possible, so organisms rely on detrital food from above or chemosynthetic energy sources near hydrothermal vents. The other zones mentioned are shallow and receive light or are defined by tidal exposure (splash and intertidal) or by being underwater near the shore (subtidal) and do not describe the permanent darkness that begins at about 1,000 meters.