16Hit1600
Expression of IdeasHardExplaining how one change reduced flooding

Expression of Ideas practice question

While researching a topic, a student has taken the following notes: - Beavers build dams across streams. - Beaver dams create ponds that hold back water. - Beavers were reintroduced to the Fell valley in 2018. - Since then, peak flood flows downstream have fallen by about a third. The student wants to explain how the beavers reduced flooding in the valley.

Which choice most effectively uses relevant information from the notes to accomplish this goal?

  1. A. Because beaver dams create ponds that hold back water, peak flood flows downstream fell by about a third after beavers were reintroduced to the Fell valley in 2018.Correct
  2. B. Beavers were reintroduced to the Fell valley in 2018.
  3. C. Peak flood flows have fallen by about a third.
  4. D. Beavers build dams across streams.

Answer: A. Because beaver dams create ponds that hold back water, peak flood flows downstream fell by about a third after beavers were reintroduced to the Fell valley in 2018.

Dams, ponds, held water, lower peaks: the mechanism and the result.

Why the other answers are wrong

B. Beavers were reintroduced to the Fell valley in 2018.
The reintroduction alone.
C. Peak flood flows have fallen by about a third.
The result without the mechanism.
D. Beavers build dams across streams.
One step of the chain.

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