Which is an example of primary succession?
A. An uninhabited cave is exposed due to recent earthquakes. Colonies of bacteria start to live in the cave.
B. A wildfire destroys most of the plants in an area. The area is repopulated by grass.
C. An invasive species of vine is outcompeting native plants. The vine grows over plants, covering and smothering them.
D. A flightless bird cannot compete with predators in an area. It gets hunted to extinction, and its niche is replaced by other animals.