Which Correctly Describes the Size and Thickness Variation in Pyroclastics

Which correctly describes the size and thickness variation in pyroclastics relative to the composite volcano they came from?

A) Size and thickness both decrease uniformly away from the central vent.
B) Size increases then decreases with distance, but deposits are the same thickness.
C) Size increases, and the deposits get thicker away from the vent.
D) Size decreases, but deposits thicken downslope and then thin with distance.