Upwellings bring cold water to the surface along with nutrients.

• A. They bring warm water to surface
• B. They bring cold water to surface and nutrients
• C. They bring oxygen to deep water
• D. They have no effect

Answer: (B)

Upwelling moves water from the deep back up to the surface, replacing what is moved away by wind-driven currents. The water rising from below is cold and carries dissolved nutrients that have accumulated in deeper layers. When these nutrients reach the sunlit surface, they fuel phytoplankton growth, leading to high biological productivity in these areas. That’s why the statement describing cold surface water along with nutrients is the best choice. The idea that upwelling brings warm water to the surface isn’t accurate, and while upwelling can affect oxygen distribution, its defining feature is the bringing up of deep, nutrient-rich water.