The correct answers are:

– introduction of non-native species;

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.

– pollution;

The pollution is a huge problem, as it is systematically destroying the environment, and the proper functioning of the ecosystems.

– overgrazing;

It is contributing to the lowering of the food sources for the wild animals.

– chemical agents;

Extremely dangerous, and poisonous for the plants and animals, either destroys their environment, or kills them directly.

– habitat loss;

The loss of the habitat effects every living organism as it is the place where they live and manage to function.