The writer's style in writing the passage can best be described as______.

A．the atmosphere has a lot of water when it circulates
B．the water in the atmosphere is purer than that in the world's oceans
C．the amount of water in the atmosphere is greater than that in the oceans of the world
D．the small 'amount of water in the atmosphere plays an important part in the rainfall on the earth

A．The volume of the atmosphere is four times that of the world's oceans.
B．The water in the oceans is the main source of rain and snow on land areas.
C．The atmosphere is mainly composed of the vapor carried over land by air currents.
D．The earth can not support the water in the atmosphere if it falls down onto the earth suddenly.