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Zorluk: ZorLogical Inferences

To trace ancient Mediterranean trade routes, archaeologists analyze trace element concentrations to source obsidian artifacts to specific volcanic flows. Strontium-to-yttrium ratios have long been used to distinguish between different obsidian sources. However, geologist Clara Vance showed that obsidian from two Melian sources, Sta Nychia and Demenegaki, has overlapping strontium-to-yttrium ratios due to a shared magmatic origin. To distinguish between them, Vance measured the barium-to-zirconium ratio, which differs significantly between the two flows due to localized crystallization during cooling. Thus, an archaeologist who detects a typical Melian strontium-to-yttrium signature in an artifact but does not evaluate its barium-to-zirconium ratio ______

Which choice most logically completes the text?

  1. A
    must conclude that strontium-to-yttrium ratios are entirely unreliable for identifying obsidian sources throughout the Mediterranean.
  2. B
    should assume that the artifact was crafted using obsidian blended from both Sta Nychia and Demenegaki.
  3. cannot definitively attribute the artifact to either Sta Nychia or Demenegaki.Cevap
  4. D
    can determine that the artifact's strontium-to-yttrium ratio was shaped by localized mineral crystallization during cooling.

Cevap

The correct answer states that the archaeologist cannot definitively attribute the artifact to either Sta Nychia or Demenegaki.
The correct answer is correct because the passage establishes that Sta Nychia and Demenegaki share overlapping strontium-to-yttrium ratios due to their shared magmatic origin, making it impossible to distinguish between them using this metric alone. Since the barium-to-zirconium ratio varies significantly between the two flows and is necessary to differentiate them, failing to measure it leaves the archaeologist unable to determine which of the two specific sources produced the artifact's obsidian.

Adım Adım Çözüm

1
Analyze the premises regarding obsidian sourcing.
Sourcing relies on strontium-to-yttrium ratios, but two Melian sources (Sta Nychia and Demenegaki) have overlapping signatures.
To understand the initial limitation of the sourcing methodology.
2
Examine the role of the barium-to-zirconium ratio.
Measuring this ratio resolves the overlap because it varies significantly between the two flows.
To identify the necessary piece of data required to distinguish the two sources.
3
Deduce the consequence of omitting the barium-to-zirconium ratio.
An archaeologist cannot determine whether the obsidian came from Sta Nychia or Demenegaki, despite knowing it is Melian.
To logically complete the passage with the only supported inference.

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Logical Inferences
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Logical Inferences

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