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Difficulty: Very hardSufficient Assumption

Paleoclimatologist: Validating any predictive model of rapid hemispheric glaciation necessitates either an uninterrupted stratigraphic record of deep-sea sediment cores or a precise quantification of atmospheric aerosol concentrations during the transition epoch. However, a precise quantification of these aerosol concentrations is strictly contingent upon the recovery of pristine ice cores from the corresponding period. Dr. Halley’s latest predictive model regarding the onset of the Younger Dryas anomaly has been conclusively validated. Yet, glaciological surveys confirm that all ice cores from the Younger Dryas transition epoch were irreparably contaminated by subsequent thermal maximums. Therefore, Dr. Halley must have been granted access to the classified geological archives held by the Nordic Subsea Consortium.

The conclusion drawn by the paleoclimatologist follows logically if which one of the following is assumed?

  1. A
    Any researcher who is granted access to the classified geological archives held by the Nordic Subsea Consortium is able to obtain an uninterrupted stratigraphic record of deep-sea sediment cores.
  2. B
    Dr. Halley’s latest predictive model regarding the onset of the Younger Dryas anomaly was not validated by means of a precise quantification of atmospheric aerosol concentrations.
  3. C
    The classified geological archives held by the Nordic Subsea Consortium contain comprehensive data regarding deep-sea sediment cores from the Younger Dryas transition epoch.
  4. The only existing uninterrupted stratigraphic records of deep-sea sediment cores for the Younger Dryas transition epoch are contained within the classified geological archives held by the Nordic Subsea Consortium.Answer
  5. E
    It is theoretically possible to achieve a precise quantification of atmospheric aerosol concentrations for the transition epoch without the recovery of pristine ice cores.

Answer

The correct answer states that the only existing uninterrupted stratigraphic records of deep-sea sediment cores for the epoch are contained within the Nordic Subsea Consortium archives.
To guarantee the conclusion, we must bridge the gap between what we logically know and what the author concludes. We know Dr. Halley validated her model. Validation requires either sediment cores (USR) or aerosol quantification (PQA). Because pristine ice cores are unavailable, PQA is impossible. Therefore, Halley must have used USR. The author concludes she accessed the Nordic Subsea Consortium (NSC). To logically guarantee this conclusion, we must assume that anyone who has USR must have accessed the NSC. The correct answer provides this exact bridge by stating the only existing USR are in the NSC archives, meaning Halley could not have gotten them from any other source.

Step-by-Step Solution

1
Map the initial requirements for model validation.
Validation requires either an Uninterrupted Stratigraphic Record (USR) OR Precise Quantification of Aerosols (PQA).
The first sentence establishes a necessary condition containing a disjunction ('either... or...').
2
Map the requirement for precise quantification.
PQA requires Pristine Ice Cores (PIC).
The second sentence explicitly states that PQA is 'strictly contingent upon' the recovery of PIC.
3
Apply the factual premises regarding Dr. Halley's model and the state of the ice cores.
Halley's model is validated. However, no PIC exist for the epoch (~PIC).
The stimulus states her model 'has been conclusively validated' and that all ice cores 'were irreparably contaminated'.
4
Deduce what Dr. Halley must have possessed to validate her model.
By modus tollens, ~PIC means ~PQA. Since Validation requires USR OR PQA, and ~PQA is true, Halley MUST have possessed USR.
The deductive chain eliminates one of the two necessary conditions for validation, leaving the other as an absolute requirement.
5
Identify the logical gap between the deduced intermediate conclusion and the author's final conclusion.
We know Halley has USR. The author concludes Halley had access to the Nordic Subsea Consortium (NSC). Gap: USR -> NSC Access.
To logically guarantee the conclusion (Sufficient Assumption), we must find an answer choice that states having USR guarantees having access to the NSC.

Key Concept

Sufficient Assumption (Formal Logic and Disjunctive Syllogism)
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Sufficient Assumption

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