Passage I
Scientists categorized each of the 300 pearly mussel species native to North America. If there were sufficient data to determine a species' risk of extinction, it was placed in 1 of 5 risk categories; otherwise, it was placed in a separate category (see Table 1).
Zebra mussels (a nonnative species) are thought to damage pearly mussel populations in North America. Zebra mussels became abundant in the Hudson River estuary in late 1992. Figure 1 shows the number of native pearly mussels in the Hudson River estuary late in each year from 1992 through 2002.
5. Which of the mussels, the zebra mussels or the pearly mussels, if either, would, when encountered in the Hudson River estuary, be considered an invasive species?
Your Answer is
Correct Answer is A
Explanation
The first sentence of the second paragraph of the article mentioned Zebra mussels (a nonnative species), and alien species are invasive species