Why Are the North Atlantic, North Pacific, and Antarctic Waters

Why are the North Atlantic, North Pacific, and Antarctic waters the most productive?

A) Phytoplankton grow there because they do not like direct sunlight.
B) Cold water holds the most dissolved oxygen and can therefore support greater numbers of phytoplankton.
C) The melt waters of the nearby ice have nutrients that are released in high quantities, fertilizing the phytoplankton.
D) Those waters are the most violently mixed, bringing up nutrients from the depths of the ocean.