Question 128·Medium·Inferences
Microplastics are tiny fragments shed from synthetic materials. In 2022, a research team collected fresh snow from a high, uninhabited plateau over 300 kilometers from the nearest town. To reduce contamination, the team used only metal sampling tools and wore cotton garments. Laboratory analysis still detected microplastic fibers, many of them dyed polyesters commonly used in clothing. The highest fiber concentrations occurred in snow that fell after two days of strong winds arriving from a coastal city roughly 400 kilometers away, whereas snow formed during calm, locally driven conditions contained far fewer fibers. Based on these observations, the researchers most reasonably inferred that _____
Which choice most logically completes the text?
For “most reasonably inferred” questions, first underline key facts and patterns (such as contrasts in conditions or cause-and-effect clues like changes over time or with wind direction). Then, test each choice against those specific details: eliminate options that (1) introduce new comparisons or global claims not in the passage, (2) contradict stated facts or controls, or (3) go far beyond what the data can support. The correct answer will be a modest, focused conclusion that fits all the evidence without exaggeration or speculation.
Hints
Focus on the wind and timing details
Reread the sentences about when the highest fiber concentrations were found. What changed between the snowfalls with many fibers and the snowfalls with fewer fibers?
Use the controls to rule out some sources
The researchers used metal tools and wore cotton garments. What type of material were the fibers mostly made of, and how does that affect which sources are likely or unlikely?
Watch for overgeneralizations
Look for answer choices that make big claims (like using words such as “more,” “most,” or broad comparisons between regions). Ask: does the passage actually provide data to support a claim that broad?
Connect location and human activity
Think about the plateau’s description (high, uninhabited, far from towns) versus the coastal city. How might this difference, combined with the wind direction, help explain the pattern in fiber concentrations?
Step-by-step Explanation
Identify the key observations in the passage
First, restate the important facts:
- The plateau is high, uninhabited, and over 300 km from the nearest town.
- The team used only metal tools and wore cotton clothing to reduce contamination.
- Lab analysis still found microplastic fibers, many of them dyed polyester used in clothing.
- The highest fiber concentrations were in snow that fell after two days of strong winds from a coastal city about 400 km away.
- Snow formed during calm, locally driven conditions had far fewer fibers.
Understand what “most reasonably inferred” means
A reasonable inference must be strongly supported by the information given, but it does not have to be directly stated.
- It must be consistent with the data and patterns described.
- It cannot introduce new claims (like “most,” “more than,” or global generalizations) that the passage doesn’t support. Keep this in mind as you test each answer against the observations from Step 1.
Connect the wind pattern to the fiber concentrations
Focus on the contrast:
- When winds came from the coastal city, fiber concentrations were highest.
- When conditions were calm and local, fiber concentrations were much lower. This pattern suggests a cause-and-effect relationship involving the direction and strength of the wind and the amount of microplastic in the snow. The plateau itself is uninhabited, and the researchers limited local contamination, so a distant source connected to the wind is implied.
Eliminate answers that overreach or contradict the setup
Now test each option against the passage:
- A) Claims the plateau receives more microplastic than the coastal city. The passage never compares the amount of deposition in the two places, so this goes beyond the data.
- B) Blames the team’s cotton clothing as the primary source, but the fibers found were polyester, and the team took steps to reduce contamination. This contradicts the setup.
- D) Says most microplastic pollution is generated by coastal cities rather than inland regions. The study only involves one coastal city; there is no global comparison of all microplastic sources. The only answer that matches the wind pattern and stays within the evidence is C, which infers that some fibers were transported long distances by wind from populated areas.