What does "it" of "since water-vapor becomes water when it cools" in Para. 3. refer to
A) Water-vapor. C) Water.
B) Cloud. D) Air.

A．It is likely to cause all clouds to give up all their rain.
B．The frequency of rainfall could be cut down, and so could the amount of rainfall.
C．In Malaysia, the monsoon often results in floods.
D．If people found ways of reducing the amount of rainfall, there would be less flood damage.

A．the rain is caused by water-vapor
B．the higher the air rises, the higher the temperature is
C．the higher the air rises, the lower the temperature is
D．the clouds rise, and the water drops become smaller