Answer:
The correct answer is a. ecological disturbance
Explanation:
Any event that disrupts the ecosystem by changing the structure of biotic communities and abiotic elements is called ecological disturbance. So ecological disturbance has a devastating effect on communities that like in that ecosystem.
These disturbances can be natural like disturbance from tsunami, volcanic eruptions, landslide, flood, etc. Disturbance created by human activities comes under artificial ecological disturbance for example disturbance created by dams.
Here the disturbance is created by digging up the grass which changes the structure of biotic and abiotic elements of that ecosystem therefore it is an example of ecological disturbance.