The image below shows part of an ocean current in the Atlantic Ocean. The blue line represents the motion of deep, cool water. The red line represents the motion of warm surface water.
One factor that affects ocean currents is the concentration of salt in the water. How can the saltiness of the water cause the surface water to sink, as shown above?
A.
When cold water rises to the surface, it loses salt.
B.
When ice melts, it makes the surface water less salty.
C.
When the surface water is heated by the Sun, it dissolves more salt.
D.
When some of the surface water freezes, the remaining water becomes saltier.