Mass flow of water; the term is usually reserved for horizontal movement.

• A. Downwelling
• B. Eastern Boundary Current
• C. Current
• D. Eddy

Answer: (C)

Mass flow of seawater in a steady, directed way is described by the term current. Currents represent horizontal transport of water across vast areas, driven by wind, the Coriolis effect, and pressure differences, so it fits the idea of a mass movement over large distances. Vertical motions, like downwelling, move water toward greater depth and aren’t about horizontal transport, so they aren’t described as currents. An eddy is a localized swirling feature that traps and moves water in a circular pattern, not the broad, sustained horizontal flow implied by mass movement. A specific example along a basin’s edge, such as a boundary current on the eastern side, is a type of current but represents only a particular instance rather than the general concept.