Which Condition Below Is Necessary for a Layer of Altostratus

Multiple Choice

Which condition below is necessary for a layer of altostratus clouds to change into altocumulus?

A) The top part of the cloud deck cools while the bottom part warms.
B) Temperature increases with increasing altitude in the layer.
C) The cloud layer becomes more stable.
D) The cloud layer becomes clear.
E) The nuclei types within the cloud have to change.