Cause–effect analogy (domain mapping): “Deterioration : Rust :: ______ : ______” — select the economic pair that mirrors a characteristic adverse outcome.

Introduction / Context:
Rust is a characteristic outcome/sign of material deterioration. In macroeconomics, widespread unemployment is a hallmark outcome of a severe downturn such as a depression. The analogy cross-maps domain-specific cause–effect signatures.

Given Data / Assumptions:

• Deterioration → Rust (in metals like iron).
• Depression → Unemployment (in economies).

Concept / Approach:
Pick a pair where the left is a broad adverse state and the right is a characteristic resulting condition.

Why Other Options Are Wrong:

• Recession : Inefficiency → inefficiency is not the canonical outcome; unemployment is more typical.
• Promulgation : Legislation → a process and a product; not an adverse-effect pairing.
• Iron : Water → materials, not cause–effect.
• Heat : Cold → opposites, not effect.

Final Answer:
Depression : Unemployment