Hmmm, going out on a limb here.
Saturation of a parcel of air occurs if the temprature of the air is lowered below depoint or the pressure increases and temp doesn't increase comensurably to prevent saturation.
So A is the classic exaple of cloud from convection. But D is significant because it states that the temprature remains constant.
A & D are, in my mind, correct!
Unless that is that Oxford Blue, Send Clowns or Alex can provide their usual reason as to why I'm wrong...again
