Answer:
Volcanic Eruption
Step-by-step explanation:
(I also know because I took the quiz) The volcano is the one that rapidly changes. It can erupt any time.
Forest Succession is slower than a volcanic eruption. It might take years for the trees in a forest to grow and for the population of animals to get there. It has to be just right, it needs all the plants and animals for it to be a forest, well not all of it but most of it.
Decomposition is also slower than a volcanic eruption.
Tree growth takes a long time. It might not even be a full tree until years later. It also takes time and water.