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Question

Difficulty: MediumPart-to-Whole Rhetorical Function

Lichenometry is a geomorphic dating technique that uses the growth rate of lichens to determine the age of exposed rock surfaces, particularly in glacial environments. Because lichen growth is highly sensitive to local microclimatic conditions such as moisture and sunlight, researchers must establish a precise local growth curve for each target species. To construct this curve, scientists measure lichens on surfaces of known historical ages, such as gravestones or dated bridge abutments. By establishing this baseline, researchers can then estimate the exposure age of undated glacial moraines with greater confidence, thereby reconstructing past glacial retreat patterns with decadal resolution.

Which choice best describes the function of the underlined sentence in the text as a whole?

  1. It describes the specific procedure used to establish the baseline measurements required for the dating method.Answer
  2. B
    It states the primary geomorphic objective of the entire field of lichenometry.
  3. C
    It identifies the historical objects that represent the ultimate focus of lichenometry studies.
  4. D
    It suggests that lichen growth is more consistent on human-made structures than on glacial moraines.

Answer

The correct option describes the specific methodology researchers use to establish the baseline measurements required for the dating technique.
The underlined sentence explains the methodology of measuring lichens on surfaces of known ages (like gravestones and bridge abutments) to build a growth curve. The following sentence states that this curve acts as a 'baseline' for estimating the age of undated glacial moraines. Therefore, the underlined sentence describes the methodology used to establish the baseline measurements required for the dating technique.

Step-by-Step Solution

1
Analyze the context before the underlined sentence.
The text explains that lichenometry requires establishing a precise local growth curve for target species because of their sensitivity to local conditions.
Understanding the problem the researchers are trying to solve (creating a growth curve) helps identify the purpose of the actions described in the underlined sentence.
2
Analyze the underlined sentence itself.
The underlined sentence states that scientists construct this curve by measuring lichens on surfaces with known historical ages, like gravestones or dated bridge abutments.
This identifies the specific action (measuring known-age surfaces) as the means to construct the required growth curve.
3
Analyze the context after the underlined sentence.
The final sentence mentions that establishing this baseline allows researchers to estimate the age of undated glacial moraines, achieving the ultimate goal of the study.
This connects the action in the underlined sentence (constructing the curve) to its function (establishing a baseline for dating moraines).
4
Synthesize the function and match with the options.
The underlined sentence describes the procedure used to create the baseline growth curve needed for dating, which matches the option describing the specific procedure to establish baseline measurements.
This verifies that the chosen option accurately reflects the logical relationship between the underlined sentence and the rest of the text.

Key Concept

Identifying the rhetorical function of a specific sentence or part of a text in relation to the text as a whole.
Estimated Time:1m 30s
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Topics

Part-to-Whole Rhetorical Function

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