Set 5: Inferences (Intermediate)

Explanation

Answer: C

PASSAGE

Rewilding projects aim to restore ecosystems by reintroducing species that were locally extinct. When wolves were brought back to Yellowstone, they reduced elk overpopulation, allowing willows to regrow, which stabilized riverbanks and created habitat for beavers and songbirds. This 'trophic cascade' showed how a single species can reshape an entire ecosystem.

What can be inferred about ecosystems?

A. Wolves had no effect on Yellowstone's ecosystem.

B. Trophic cascades are purely theoretical concepts.

C. Removing or adding key species can trigger cascading effects throughout the system.✓ Correct

D. Each species exists independently of others.

Detailed Explanation

This question asks you to draw a logical conclusion from the text. Wolves → fewer elk → willows → riverbanks → beavers/birds = cascading effects from one species. A valid inference must be supported by evidence in the passage, even if not stated directly. Look for clues in the text that strongly suggest the answer. Avoid conclusions that require assumptions beyond what's written. Valid inferences are strongly supported by multiple pieces of evidence in the text. Be cautious of choices that go too far beyond what the passage actually states. The best inference is the one most directly supported by textual evidence.

Key Evidence:

• "trophic cascade"

• "a single species can reshape an entire ecosystem"

Why others are wrong: A (The passage describes major effects.), B (Yellowstone is a real example.), D (The cascade shows interconnection.).

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