Cold dense polar water sinks, then spreads towards the equator where it pushes up the less dense warmer water which moves off towards the polar areas.

• A. Rises, Equator
• B. Sinks, Polar
• C. Sinks, Equator
• D. Rises, Polar

Answer: (B)

The key idea is density-driven ocean circulation, often called the thermohaline conveyor. At the poles, surface water becomes very cold (and often saltier), increasing its density. That dense polar water sinks and then flows away from the pole along the deep ocean. In this deep flow, it pushes up the lighter, warmer water elsewhere, which then moves back toward the polar regions at the surface to complete the cycle. So the process starts with water sinking, and the movement described is tied to the polar regions as the source and part of the return path, which fits the idea of sinking water connected to polar areas.