Nonnative species can harm some populations in an ecosystem why

Nonnative species can be harmful to the environment because it has not adapted to that environment. It also disturb other species on their food cycles and living. 

An organisms niche is (A) The range of physical and biological conditions in which an organism lives and the way in which it uses those conditions.
 Technically, any of the answers could be true, however, A is the only one that offers a broad definition.A niche is not only the location and conditions in which an organism lives, but also the organisms role within that niche and how it uses the resources to survive.