Stability returns to disrupted ecosystems because

The components of the ecosystem become adapted to the changed conditions.

Explanation:

Any changes that disrupt the normal functioning of the ecosystem make it unstable. However, the species of the living beings present the disturbed ecosystem evolve adaptive features to adjust themselves towards the changed conditions.  

Gradually, the components of the ecosystem become adapted to the changes and the disturbed ecosystem becomes stable again.  

1. b.

2. d.

3. a.

5. d.

6. c.

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