The correct answers are:
<em>- introduction of non-native species;</em>
The invasive species are often very dangerous for the native species, and that is because they manage to out-compete them for the needed resources.
<em>- pollution;</em>
The pollution is a huge problem, as it is systematically destroying the environment, and the proper functioning of the ecosystems.
<em>- overgrazing;</em>
It is contributing to the lowering of the food sources for the wild animals.
<em>- chemical agents;</em>
Extremely dangerous, and poisonous for the plants and animals, either destroys their environment, or kills them directly.
<em>- habitat loss;</em>
The loss of the habitat effects every living organism as it is the place where they live and manage to function.