Thanks for the question! Basically, we’re being asked here for a question that both of the passages can answer. So the correct answer choice is something that’s going to be able to be answered in both passages.
Now take a look at (E), which states that both of the passages can answer the following question: what’s a type of terrain that’s affected in at least some parts of North America by the presence of purple loosestrife? Well, can passage A answer this question/ Yes, passage A talks about some terrain that’s affected, like “the continent’s midlatitude wetlands” (lines 4-5) and later the wetland communities. So passage A can answer that question.
Now can passage B answer this question? Well, look at the very end of passage B, which says that the purple loosestrife will lead to “a decline in the production of the wetland resource” (lines 64-65). So passage B can also answer this question, the purple loosestrife affects the wetlands! And since both the passages can answer (E), then it’s the correct answer.
Hope this helps! Feel free to ask any other questions that you might have.
