______is not the cause of the decrease in the oceanic salinity.

A．the subtraction of water
B．the conversion of liquid water to water vapor
C．the salinity of ocean water
D．the effect of precipitation on the salinity of ocean water

A．give an example of cold water salinity
B．point out the location of deep waters
C．compare Antarctic waters with Arctic waters
D．indicate that this body of .water has salinity variations