Various plant and animal species are on the verge of extinction.

Because all organisms are 1. to their native habitat, human activities that result in 2. are the major reason for their extinction.

For number 1:
A.) adapted
B.) fragmented
C.) unattached

For number 2:
A.) habitat destruction
B.) habitat reconstruction
C.) habitat restoration

  1: A.) adapted

  2: A.) habitat destruction

Explanation:

Some (few) animals are capable of adjusting their behaviors in relation to human activity and the changes humans make in their habitat. Most are so well adapted to the details of their habitat that they are incapable of surviving when those details change.

"Because all organisms are adapted to their native habitat, human activities that result in habitat destruction are a major reason for their extinction."

Comment on human activities

My friendly local rodent exterminator observed that rodent activity has picked up substantially, since so much human activity has been curtailed by quarantine orders.