Which upwelling occurs when water moving westward near the equator is deflected poleward and replaced by nutrient-rich deep water?

• A. Gulf Stream
• B. Float Method
• C. Equatorial Upwelling
• D. Geostrophic Gyre

Answer: (C)

Equatorial upwelling is driven by wind-driven surface flow and the way the Coriolis effect changes with latitude. Trade winds push surface water west along the equator, and as you move away from the equator the Coriolis force deflects that water toward the poles. This creates a divergence of surface water right at the equator, so deeper, nutrient-rich water rises to replace what is moved away. The upwelled water brings nutrients to the surface, fueling high productivity in these regions.

That’s why this option fits best: it describes the process where westward-moving surface water near the equator is replaced by deeper water rising up, bringing nutrients. Other choices refer to different ocean features or methods (a warm boundary current, a measurement technique, or a large-scale circular pattern) and don’t describe this nutrient-rich deep-water upwelling.