The secondary ecological succession begins in an area, where:

The correct answer is Option (3) → Natural biotic communities have been destroyed

Option (1) Species invade a bare land/rock — Incorrect. Invasion of bare land or rock is primary succession.

Option (2) Vegetation has been grazed by Cattles — Incorrect. Grazing alone does not remove the community or the soil.

Option (3) Natural biotic communities have been destroyed — Correct. Option (3) describes secondary succession: life returns to a place where a community once stood and some soil or sediment is still there. Bare land or rock (option 1) is where primary succession starts instead.

Option (4) Natural biotic communities are flourishing — Incorrect. A flourishing community does not need to start over.

Note: This question is from the topic “Ecological Succession” in Chapter 14, Ecosystem, of the pre-rationalised NCERT book. This portion is not in the present NCERT book, where the chapter is now Chapter 12, Ecosystem. The extract below is from the pre-rationalised edition.

NCERT Extract (Pre-rationalised edition, Chapter 14, Ecosystem):
Ecological Succession – “… Secondary succession begins in areas where natural biotic communities have been destroyed such as in abandoned farm lands, burned or cut forests, lands that have been flooded. Since some soil or sediment is present, succession is faster than primary succession.”