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Difficulty: MediumWords in Context: High-Utility Vocabulary

For decades, many paleontologists hypothesized that the extinction of non-avian dinosaurs was a gradual, protracted process driven primarily by long-term volcanic eruptions that slowly altered the global climate. However, recent analyses of high-resolution sediment cores from the end of the Cretaceous period have ______ this theory. These geologic records reveal a sudden, global layer of iridium and shock-deformed quartz—telltale signatures of a massive asteroid impact—that coincides precisely with the sudden disappearance of these species from the fossil record.

Which choice completes the text with the most logical and precise word or phrase?

  1. A
    corroborated
  2. underminedAnswer
  3. C
    scrutinized
  4. D
    introduced

Answer

undermined
The correct option is 'undermined'. The passage contrasts the long-held hypothesis that dinosaur extinction was a gradual volcanic process with new evidence of a sudden asteroid impact. The transition word 'However' signals that the new findings challenge or weaken the established theory, which is precisely what 'undermined' means.

Step-by-Step Solution

1
Analyze the context of the blank to identify the relationship between the two main ideas in the text.
The text contrasts a traditional theory (gradual extinction by volcanoes) with recent geological findings (sudden extinction by an asteroid impact), marked by the transition 'However.'
Understanding the logical flow helps determine if the missing word should denote support, contradiction, or neutral action.
2
Determine the required meaning of the word that fits the blank.
Since the recent findings contradict the volcanic theory, the blank must be filled by a word meaning to weaken, challenge, or cast doubt upon the theory.
This establishes the target definition to match against the options.
3
Evaluate the choices to find the word that best matches the target definition.
'Undermined' means to weaken or subvert, which perfectly fits the context. The other options either contradict the contrast ('corroborated'), are contextually illogical ('introduced'), or fail to describe the effect of the new findings on the theory ('scrutinized').
Selecting the most precise and contextually accurate vocabulary word completes the task.

Key Concept

Identifying contextual clues, such as contrast transitions and evidence, to determine the most precise word that describes the relationship between scientific hypotheses.
Estimated Time:1m 0s
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Topics

Words in Context: High-Utility Vocabulary

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