Purple Loosestrife, Lythrum Salicaria, Is a Beautiful, Long-Stemmed Wetlands Species

Purple loosestrife, Lythrum salicaria, is a beautiful, long-stemmed wetlands species brought to the United States from Europe as an ornamental plant. In the United States, it has no predators and crowds out cattails, Typha latifolia, another wetlands plant that's a valuable resource for many species. Purple loosestrife is an example of

A) an introduced species.
B) a parasite.
C) a predator.
D) overexploitation.