In Tropical Regions the Surface Temperature of the Oceans Is

In tropical regions the surface temperature of the oceans is high but decreases rapidly with depth between 300 and 1000 meters because ________.

A) rapidly upwelling cold currents occur in these regions
B) cold water from the polar regions flows just below the surface
C) volcanic activity on the seafloor is rare in the tropics
D) sunlight cannot penetrate much below the surface of the oceans
E) tropical regions are areas of high rainfall and this rapidly lowers the temperature of seawater