Question 97·Easy·Inferences
Researchers studying a remote desert lake used satellite images collected over several years. They noticed that the lake’s water level dropped sharply whenever a month had many unusually strong windstorms. The team proposed a reason: strong winds blow away the fine layer of dust that normally drifts above the lake, and without this dust to shade the surface, more sunlight reaches the water and speeds up evaporation.
If the researchers’ proposal is correct, a lengthy stretch of calm weather with very few windstorms would most likely cause the lake to _____
Which choice most logically completes the text?
For inference questions like this, first restate the cause-and-effect relationship given in the passage in simple steps (A causes B, which causes C). Then, when the question asks about a new or opposite situation, mentally apply the same chain in reverse or to the new condition, without adding outside knowledge. Finally, match your predicted outcome (in this case, what happens to the dust, sunlight, and evaporation in calm weather) to the answer choice that stays closest to the passage’s logic and does not introduce new, unsupported ideas.
Hints
Identify the cause-and-effect chain
Focus on the explanation the researchers give: what do strong winds do to the dust, and how does that change sunlight and evaporation?
Reverse the situation
The passage talks about what happens when there are many strong windstorms. The question asks about a lengthy stretch of calm weather. Think about what would be the opposite of the situation described.
Track the role of the dust layer
Ask yourself: In calm weather, what likely happens to the dust layer above the lake, and how would that affect how much sunlight hits the water and how fast it evaporates?
Step-by-step Explanation
Restate the scientists’ explanation in simple terms
First, translate the researchers’ proposal:
- Normally, there is a fine layer of dust drifting above the lake.
- This dust shades the lake’s surface.
- Strong winds blow the dust away.
- Without the dust, more sunlight hits the water.
- More sunlight on the water speeds up evaporation, so the water level drops.
Think about what happens when there are few windstorms
The question now asks about "a lengthy stretch of calm weather with very few windstorms."
If strong winds remove the dust, then very few windstorms means:
- The dust is not being blown away.
- The dust layer can stay above the lake (and maybe even build up more).
- So the lake’s surface stays more shaded.
Connect shade, sunlight, and evaporation
From the explanation, the key chain is:
- More sunlight on the water → faster evaporation → water level drops more.
- Less sunlight on the water (more shade) → slower evaporation → water level drops less.
During calm weather, the dust stays and shades the lake, so less sunlight reaches the surface and evaporation slows down.
Match the logical outcome to the answer choices
We want the choice that says the lake would lose water more slowly (keep more water) because less sunlight reaches it.
Choice C, "keep more of its water because less sunlight would reach the surface," directly matches this reasoning and is therefore the correct answer.