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Difficulty: MediumEstablishing Introductions and Thesis Statements

The following is an excerpt from an essay about geological discoveries.

[1]
__________________________________________________ Prior to Danish seismologist Inge Lehmann's groundbreaking publication in 1936, scientists believed that the Earth's core was a single, uniform liquid sphere. By analyzing seismic waves from a major earthquake in New Zealand, Lehmann observed that some P-waves were unexpectedly deflected, or diffracted, deep within the Earth. She reasoned that this deflection could only be caused by a distinct, solid inner core nested inside the liquid outer core. Her hypothesis was eventually confirmed by more advanced instruments, redefining the field of seismology.

Which choice provides the most effective introduction to the paragraph?

  1. In 1936, Danish seismologist Inge Lehmann published a paper that fundamentally altered our understanding of Earth's interior.Answer
  2. B
    Seismology, which involves the study of earthquakes and seismic waves, help scientists understand natural disasters.
  3. C
    Although the Earth's core is composed of heavy metals like iron and nickel.
  4. D
    Earthquakes generate several types of seismic waves; which travel through the planet's layers.

Answer

The correct option is the sentence introducing Inge Lehmann's 1936 publication, as it is grammatically correct and directly establishes the topic of the passage.
The correct option successfully introduces the main topic of the paragraph, which is Danish seismologist Inge Lehmann's discovery of the Earth's solid inner core. It is grammatically correct and flows logically into the subsequent sentence that describes beliefs prior to Lehmann's publication.

Step-by-Step Solution

1
Analyze the main focus of the paragraph.
The paragraph discusses the discovery of the Earth's solid inner core by Inge Lehmann in 1936, contrasting her findings with prior beliefs about a uniform liquid core.
Understanding the central theme is necessary to identify which sentence best introduces the topic.
2
Evaluate the options for grammatical correctness and relevance.
The correct choice must be a complete, grammatically correct sentence that introduces Lehmann or the core structure discovery. The other options contain grammar errors (subject-verb agreement, fragments, or incorrect semicolon usage) and focus on off-topic details like wave types, core composition, or general seismology.
Eliminating grammatically flawed and off-topic sentences leaves the option that serves as a proper topic sentence.
3
Select the option that establishes a clear transition into the next sentence.
The statement introducing Lehmann's 1936 publication perfectly sets up the contrast in the next sentence: 'Prior to Danish seismologist Inge Lehmann's groundbreaking publication in 1936, scientists believed...'
An effective introduction must connect logically to the sentences that follow it.

Key Concept

Establishing an effective introduction that matches the focus of the paragraph while maintaining grammatical correctness.
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Topics

Establishing Introductions and Thesis Statements

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