Fronts Are Associated with Clouds Because

Fronts are associated with clouds because

A) the warm air rises and cools adiabatically over the cooler air.
B) the warm air is stable and cooled by radiation escaping to space.
C) the cold air of the cold front can't hold as much moisture, so it becomes cloud banks.
D) when air moves it becomes opaque.
E) friction along the front heats the air and makes clouds.