The Deep Zone of the ocean is characterized by?

• A. Shallow, sunlit and warm
• B. Surface mixed layer with variable salinity
• C. Deep, dark, cold, high pressure
• D. Brackish water near coastlines

Answer: (C)

Think about what happens as you go deeper in the ocean. The Deep Zone lies far below the sunlit layers, where there’s essentially no light for photosynthesis. With that lack of light, the water stays cold, and the pressure increases very, very high because of the immense column of water above. So the defining features are depth, darkness, cold temperatures, and high pressure.

The other options describe conditions at shallower or different environments: a shallow, sunlit and warm water body is the surface zone; a surface mixed layer with variable salinity describes the uppermost mixed layer affected by wind and freshwater input; brackish water near coastlines refers to estuarine areas where river water mixes with seawater.