Which zone comprises plains and hills and accounts for about 80% of the benthic environment?

• A. Abyssal Zone
• B. Bathyal Zone
• C. Disphotic Zone
• D. Euphotic Zone

Answer: (A)

The main idea here is recognizing the deep-sea bottom features and where they dominate. The abyssal zone covers the deep ocean floor beyond the continental margins, where the seafloor is shaped by vast abyssal plains (flat or gently undulating sediment-covered areas) and abyssal hills (subtle elevations). These plains and hills make up the bulk of the benthic environment, accounting for a large portion—often cited around 80% of the ocean bottom. The other options refer to light regimes in the water column (euphotic and disphotic) or to deeper, slope-related areas (bathyal), which don’t match the flat-to-hilly seafloor description.