Answer:
The correct option is <em>3. they break down rock into soil in which plants can grow</em>
Explanation:
When a disaster is such huge that even the soil and organic matter get removed from the place, then the succession that will occur in such kind of place will be termed as primary succession. For example, a volcanic eruption or an earthquake.
On the other hand, if after a disaster some of the organic matter remains on the land, then the succession that will occur will be termed as secondary succession. E.g a succession after fire
In primary succession, the pioneer species will be plants that require less soil such as the lichens. The lichens will break down the rocks into the soil and eventually new species of plants will start to grow on the land.
