Classification (association): In three pairs, the first item is the input/resource used by the second; in one pair the relation is different. Identify the odd pair.

Introduction / Context:
Association-based classification checks whether the semantic relation is consistent across options. Here, the pattern is “resource used by device/tool.” One pair deviates because the first item is not a resource used by the second; rather, it is what the second removes.

Given Data / Assumptions:

• Petrol powers a car.
• Electricity powers a television.
• Ink is a resource used by a pen to write.
• Dust is not a resource used by a vacuum cleaner; it is the unwanted material removed.

Concept / Approach:
Identify device→resource pairs. The odd pair will invert or contradict the resource direction.

Step-by-Step Solution:

Verification / Alternative check:
Paraphrase as “X is used by Y to function.” Only dust fails this template.

Why Other Options Are Wrong:

Common Pitfalls:
Confusing “input” vs “output/waste.” Dust is not an input to vacuum cleaners.

Final Answer:
Dust-Vacuum Cleaner