What Role Does Disturbance Play in the Recently Discovered Mechanism

What role does disturbance play in the recently discovered mechanism of pond succession that isn't found in the classical mechanism of succession?

A) Droughts lower water levels so that plants can colonize lake sediments.
B) Rushing water scours the bottom of the lakes, allowing diatoms to colonize.
C) Glaciers scour the land, leaving depressions that can fill up with melting water.
D) Peat fires remove the vegetation, allowing secondary succession to proceed.