Question

Which of the following could result in secondary succession?
the formation of a tall sand dune on a previously grassy beach
a vast glacier in motion forming a U-shaped valley on its wake
a volcanic eruption that covers most of what used to be a forest
an introduced species that devastates native plants as it feeds

Answer 1

a volcanic eruption that covers most of what used to be a forest

Answer 2

C because here new plants will grow where earlier there were also plants. this is not primary succesion because in primary succesion, plants start growning where there were no plants before.