Passage Summary: We plant grass and shrubs to stop dirt from washing away, but then we mow the grass. The cut grass kills the plants by smothering them and by attracting mice that eat the roots. The author thinks just getting rid of the mice will solve the whole erosion problem.

Conclusion: Introducing predators to eliminate rodents will be sufficient to stop the erosion of the embankments.

Reasoning: Rodents damage the roots of the plants that prevent erosion, and these rodents are attracted to the grass clippings created by mowing.

Analysis: The author identifies two distinct causes of root damage—smothering by clippings and rodent burrowing—but then suggests a solution that only addresses the rodents. Even if the predators are highly efficient hunters, the piles of clippings remain, still smothering the plants and causing rot. Look for an answer that points out the failure to address all sufficient causes of the problem. It is a classic case of a 'partial solution' being mistaken for a 'total fix' in a complex system.