Answer:
d. where deep ocean water currents are formed.
Explanation:
Upwelling is the process in which the cold water beneath the surface of the ocean is pushed up and replaces the water on the surface.
Upwelling usually happens along the coasts of the continents (such as west coasts of the northern hemisphere for the example - here, the northern winds are responsible), like the edge od the Pacific ocean and Atlantic ocean, Western Africa, etc.
