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Difficulty: HardMust Be True / Most Strongly Supported

An environmental audit of reclaimed sub-boreal wetland zones established the following criteria for ecosystem stabilization:

• Any wetland zone that undergoes successful peat layer restoration exhibits stable anaerobic methanogenesis, unless it experiences persistent sulfur runoff.
• Every wetland zone that exhibits stable anaerobic methanogenesis maintains a neutral pH level throughout its rooting substrate.
• No wetland zone that maintains a neutral pH level in its rooting substrate supports the proliferation of invasive reed canary grass.
• During the previous assessment cycle, Zone 14 underwent successful peat layer restoration and did not experience persistent sulfur runoff.

If the statements above are true, which of the following statements must also be true? (Select all that apply.)

  1. Zone 14 maintains a neutral pH level throughout its rooting substrate.Answer
  2. B
    Every wetland zone in the audit that maintains a neutral pH level throughout its rooting substrate underwent successful peat layer restoration.
  3. Any wetland zone in the audit that supports the proliferation of invasive reed canary grass does not exhibit stable anaerobic methanogenesis.Answer
  4. D
    Any wetland zone in the audit that experiences persistent sulfur runoff will invariably support the proliferation of invasive reed canary grass.
  5. E
    Zone 14 is the only wetland zone evaluated in the audit that does not support the proliferation of invasive reed canary grass.

Answer

The statements establishing that Zone 14 maintains a neutral pH level throughout its rooting substrate and that any wetland zone supporting invasive reed canary grass proliferation does not exhibit stable anaerobic methanogenesis must both be true.
The deduction concerning Zone 14 directly follows from a complete forward chain through the conditional rules triggered by its factual premises. The deduction concerning any zone with canary grass proliferation represents a valid contrapositive linking the absence of proliferation back to the absence of stable anaerobic methanogenesis.

Step-by-Step Solution

1
Diagram the formal conditional rules from the stimulus.
Rule 1: (Peat Restoration AND NOT Sulfur Runoff) → Stable Methanogenesis. Rule 2: Stable Methanogenesis → Neutral pH. Rule 3: Neutral pH → NOT Invasive Canary Grass Proliferation.
Establishing explicit conditional chains allows for unambiguous forward deductions and contrapositives.
2
Evaluate the factual findings regarding Zone 14.
Zone 14 satisfies both components of the antecedent in Rule 1, establishing that Zone 14 exhibits Stable Methanogenesis → Neutral pH → NOT Invasive Canary Grass Proliferation.
Modus ponens guarantees each successive necessary condition for Zone 14.
3
Derive universal contrapositive inferences for the entire audited population.
By linking Rule 2 and Rule 3: Stable Methanogenesis → NOT Invasive Canary Grass Proliferation. The contrapositive is: Invasive Canary Grass Proliferation → NOT Stable Methanogenesis.
A conditional claim and its contrapositive are logically equivalent.

Key Concept

Deductive Conditional Chaining and Contrapositive Inference
Estimated Time:2m 0s
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Topics

Must Be True / Most Strongly Supported

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