Classification (resource requirement): Three pairs show a resource required by the second item; one pair reverses the direction (source → content). Identify the odd pair.

Introduction / Context:
This mirrors a common association question: does the first item function as an input needed by the second? Three options do; one instead names a source that supplies the first item, flipping the relation and creating the outlier.

Given Data / Assumptions:

• Oil is needed by a lamp (fuel).
• Power is needed by a machine (energy).
• Oxygen is needed for life (biological requirement).
• Water : Tap indicates that the tap supplies water; the direction is source→substance, not requirement.

Concept / Approach:
Test each as “X is required by Y.” The outlier fails this template because Y is a supplier, not a consumer of X.

Step-by-Step Solution:

Verification / Alternative check:
Swap order for the odd pair: Tap : Water would align with source→product, confirming misdirection in the given pair.

Why Other Options Are Wrong:

Common Pitfalls:
Ignoring directionality and accepting any association as valid. The logic hinges on “needed by.”

Final Answer:
Water : Tap