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Difficulty: HardSufficient Assumption

Botanist: Any alpine plant that undergoes early budburst without a corresponding increase in foliar cuticle thickness will suffer extensive cellular necrosis if exposed to unseasonal late-spring freezes. Furthermore, any plant that suffers extensive cellular necrosis from late-spring freezes will experience a reduction in lifetime seed viability below the replacement threshold unless it can activate dormant meristem tissue. Southern dwarf willows invariably undergo early budburst in response to early-season warming, yet they completely lack dormant meristem tissue. Therefore, if unseasonal late-spring freezes occur in their habitat, southern dwarf willows will experience a reduction in lifetime seed viability below the replacement threshold.

The botanist's conclusion follows logically if which one of the following is assumed?

  1. A
    Any alpine plant that experiences a reduction in lifetime seed viability below the replacement threshold must have suffered extensive cellular necrosis from late-spring freezes.
  2. B
    Unseasonal late-spring freezes are the primary cause of cellular necrosis in alpine plants that lack dormant meristem tissue.
  3. Southern dwarf willows do not develop increased foliar cuticle thickness when they undergo early budburst.Answer
  4. D
    Activating dormant meristem tissue is always sufficient to prevent an alpine plant from suffering extensive cellular necrosis during late-spring freezes.
  5. E
    Southern dwarf willows that avoid exposure to unseasonal late-spring freezes will maintain lifetime seed viability at or above the replacement threshold.

Answer

The statement that southern dwarf willows do not develop increased foliar cuticle thickness when they undergo early budburst guarantees the conclusion.
The correct response supplies the precise missing premise needed to complete the conditional syllogism. Premise 1 states that early budburst combined with a lack of foliar cuticle increase leads to necrosis during a freeze. Premise 2 states that necrosis combined with a lack of dormant meristem tissue leads to sub-replacement seed viability. The stimulus states that southern dwarf willows experience early budburst and lack dormant meristems. By establishing that southern dwarf willows do not increase foliar cuticle thickness during early budburst, every necessary condition in the chain is satisfied when a freeze occurs, making the conclusion deductively valid.

Step-by-Step Solution

1
Deconstruct the formal conditional chain in the premises
Premise 1 establishes: (Alpine Plant + Early Budburst + No Cuticle Increase + Freeze) -> Cellular Necrosis. Premise 2 establishes: (Cellular Necrosis + No Dormant Meristems) -> Seed Viability Below Replacement. Factual evidence confirms southern dwarf willows undergo early budburst and lack dormant meristems.
Mapping the explicit conditional statements reveals the exact logical gap required to bridge the premises to the conclusion.
2
Identify the inferential gap between the conditional triggers and the conclusion
To reach the conclusion that a freeze guarantees seed viability falling below the replacement threshold, the condition for Cellular Necrosis must be fully satisfied. We know southern dwarf willows undergo early budburst, but we are not told whether they experience an increase in foliar cuticle thickness.
If southern dwarf willows develop increased cuticle thickness, the first conditional rule would not trigger cellular necrosis, leaving the conclusion unproven.
3
Select the assumption that completely closes the deductive gap
Assuming that southern dwarf willows do not develop increased foliar cuticle thickness when undergoing early budburst completes the antecedent of Premise 1 upon exposure to a freeze, which guarantees cellular necrosis and consequently drives seed viability below replacement.
A sufficient assumption must guarantee that the premises 100% logically entail the conclusion without exception.

Key Concept

Sufficient Assumption in Deductive Conditional Chains
Estimated Time:2m 0s
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Topics

Sufficient Assumption

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