Which environmental changes occur fastest. volcanic eruption. pond succession. decomposition of a tree. regrowth of forest after volcanic eruption

The correct answer is A
volcanic eruption
Volcanic eruption is defined as the sudden rush of energy materials such as gas,lava and steam.  all the others processes takes a great deal of time. For example decomposition takes a long time. Pond succession is dependent on settling of debris and hence takes a long time. regrowing of a forest after a a volcanic eruption can span several years,especially if indigenous trees are the main tree species.