Read the passage carefully and give the answers to the question :
Does the number of species in a community really matter to the functioning of the ecosystem? This is a question for which ecologists have not been able to give a definitive answer. For many decades, ecologists believed that communities with more species, generally, tend to be more stable than those with less species.
According to the International Union for Conservation of Nature and Natural Resources (IUCN) (2004), the total number of plant and animal species described so far is more than 1.5 million.
Which of the following is not a characteristic of a stable biological community?

1. A It must be resistant to invasions by alien species.
2. B It should not show too much variation in productivity from year to year.
3. C All the species are equally important in a stable community and absence of any one leads to its unstability.
4. D It is resilient to occasional disturbances, whether natural or man-made.