Question 34·Easy·Inferences
Researchers analyzing nineteenth-century shipping logs from vessels docked in the northern port of Crestwick noted repeated references to ice forming on the harbor in early November, whereas weather-station records from the last 50 years show the harbor has not begun to freeze before mid-December. Based on this information, the researchers concluded that ______
Which choice most logically completes the text?
For SAT “based on this information, the researchers concluded that” questions, first restate the key evidence in your own words, focusing on the change or pattern described. Then look for the answer that directly summarizes that pattern without adding new ideas, causes, or assumptions. Quickly rule out any choices that speculate about motives, accuracy, or unmentioned factors (like different locations or equipment), since valid conclusions must come straight from what the passage says or clearly implies.
Hints
Compare the two time periods
Look carefully at what the nineteenth-century logs say about when ice formed and what the modern weather-station records say about when freezing begins now. How are those times different?
Think about what a later freezing date implies
If the harbor used to freeze earlier in the year but now freezes later, what does that say about how long the harbor stays ice-free each year?
Watch out for extra assumptions
Some choices introduce ideas about people’s honesty, instrument accuracy, or station locations. Ask yourself: are those ideas mentioned or implied in the text, or are they being invented?
Look for the most direct summary
Which option simply summarizes the change described by the data—without adding any new explanations or accusations?
Step-by-step Explanation
Locate the key pieces of evidence
First, focus on what specifically changed over time.
- Nineteenth-century logs: repeated references to ice forming on the harbor in early November.
- Last 50 years: weather-station records show the harbor has not begun to freeze before mid-December. So the freezing date has shifted from early November to mid-December.
Translate the evidence into a general trend
If the harbor used to freeze in early November but now does not freeze until mid-December, then:
- The period before freezing (when the harbor is ice-free) is now longer than it used to be.
- In other words, the harbor remains free of ice for more days each year than it did in the nineteenth century. Keep this general idea in mind when checking the answer choices.
Eliminate choices that introduce new, unsupported ideas
Now compare each choice to the evidence:
- Choice A talks about mariners exaggerating severe weather. The passage gives no hint they lied or exaggerated; it treats their logs as data.
- Choice B claims modern weather stations are much farther inland. The passage never mentions moving locations, only the timing of freezing.
- Choice C says nineteenth-century crews lacked accurate instruments. But the conclusion comes from their logs plus modern records, so the researchers clearly trusted the old observations. All three bring in extra claims not mentioned in the text, so they are not logically supported by the given information.
Select the choice that directly restates the supported conclusion
The remaining idea is that, compared with the nineteenth century, the harbor now freezes later in the year, implying a longer span of ice-free days each year. The only option that directly and accurately captures this change—without adding new assumptions—is choice D: the harbor has experienced a lengthening of ice-free conditions over the past century.