Which causes the thermocline?
a.
the sun’s radiation heats the surface waters, which descend to the depths and bring colder water to the surface.
b.
the sun’s radiation heats equatorial waters more than polar waters.
c.
the sun’s radiation does not extend below a certain depth; therefore, deeper ocean water is colder than surface water.
d.
the sun’s radiation heats surface waters, causing them to spread out and bring up colder water from the depths.

Thermocline is a layer between warm water from the ocean’s surface and cool water from below the ocean. In here, the temperature decreases rapidly from the warmer layer to the colder layer.  A thermocline forms due to the heat of the sun heating the ocean’s surface. Because of the difference in density between warm and cooler ocean water, cooler ocean water sinks and warmer ocean water floats. This is caused due to the heat and mass transfer between particles of the ocean. The answer is letter C. The sun’s radiation does not extend below a certain depth; therefore, deeper ocean water is colder than surface water.