What characteristic should a stable community exhibit?

The correct answer is Option (2) → Resistance or resilience to occasional disturbances

Ecologists long believed that communities with more species tend to be more stable. NCERT describes a stable community by three features: it should not show too much variation in productivity from year to year, it must be either resistant or resilient to occasional disturbances, natural or man-made, and it must be resistant to invasions by alien species.

Option (1) High variation in productivity from year to year — Incorrect. A stable community should show little variation in productivity from year to year, not high variation.

Option (2) Resistance or resilience to occasional disturbances — Correct. Being able to resist a disturbance, or to recover from it, is one of the features of a stable community.

Option (3) High susceptibility to invasions by alien species — Incorrect. A stable community must be resistant to invasions by alien species, not easily invaded.

Option (4) Constant changes in species composition — Incorrect. Constant change in species composition is not listed as a feature of stability; a stable community keeps its working steady.

NCERT Extract:
The Importance of Species Diversity to the Ecosystem – “… For many decades, ecologists believed that communities with more species, generally, tend to be more stable than those with less species. What exactly is stability for a biological community? A stable community should not show too much variation in productivity from year to year; it must be either resistant or resilient to occasional disturbances (natural or man-made), and it must also be resistant to invasions by alien species.”