SAT OwlQuestion bank / Central Ideas and Details
Mountain pine beetles have always attacked pine trees in western North America, but outbreaks have grown far larger since the 1990s. In the past, winter cold snaps of minus 40 degrees Celsius killed most of the beetle larvae sheltering under bark, keeping populations in check. As such cold snaps have become rarer, more larvae survive to adulthood. Drought has also weakened many trees, making it harder for them to produce the sticky resin they use to push out attacking beetles.
According to the text, how does drought contribute to larger beetle outbreaks?
It causes winter temperatures to fall below minus 40 degrees Celsius.
It kills beetle larvae that shelter beneath bark.
It weakens trees so that they produce less of the resin that pushes out attacking beetles.
It forces beetles to move into forests at higher elevations.
Show answer and explanation
Answer: C
The last sentence says drought weakens trees, "making it harder for them to produce the sticky resin they use to push out attacking beetles." With weaker defenses, more beetles succeed. That is choice C.
Choice B mixes up the two factors: it is extreme cold, not drought, that kills larvae under the bark.
Why the other choices are wrong
- A. The text states that cold snaps have become rarer, not that drought causes temperatures to drop below minus 40 degrees Celsius.
- B. Extreme cold, not drought, is the factor described as killing beetle larvae sheltering beneath the bark.
- D. The passage does not mention beetles moving to higher elevations; it focuses on tree weakness and reduced resin production.
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