Answer:
A. an introduced species.
Step-by-step explanation:
Purple Loosestrife is an introduced speicie. An introduced specie is an organism that is typically not a native of a particular ecosystem. i.e they are foreign species. The can either be transferred accidentally through dispersal of wind or directly by human activities. Introduced Species do contribute to the nature of the ecosystem in a great way. The impact and aftermath effect of introduced species varies from one distributional range to another. It can either be a positive contribution or a negative contribution. Some species have been introduced intentionally to combat pests. These species are popularly termed biocontrols and may be regarded as beneficial as an alternative to pesticides.