The portion of the ocean floor where light does not penetrate and where temperatures are cold and pressures intense. Although it touches the bottom of the ocean, it does not include sediment or the benthic zone:

• A. Benthos
• B. Intertidal zone
• C. Pelagic zone
• D. Abyssal zone

Answer: (D)

The concept being tested is how the ocean is divided by depth into distinct life zones, based on light, temperature, and pressure. The abyssal zone is the deep, dark, high‑pressure part of the ocean, typically around 4,000 to 6,000 meters deep, where no sunlight reaches and temperatures are near freezing. It’s a region defined by depth and the resulting environmental conditions, not by what lies on the seafloor.

It touches the bottom in the sense that many of these depths extend to the abyssal plains on the ocean floor, but it isn’t the benthic zone itself. The benthic zone refers to the bottom habitat and its organisms living in or on the sediment. The abyssal zone, by contrast, describes the deep water layer near that bottom, a part of the pelagic realm. In short, you’re dealing with the deepest, dark, high‑pressure waters, adjacent to the seabed but distinct from the sediment‑dwelling benthos.