Classification — product vs material: identify the single pair that is in the reverse direction compared to the others.

Introduction / Context:
Three pairs name a product followed by a typical material it is made from (product → material). One pair flips the direction and lists the material first and the product second.

Given Data / Assumptions:

• Shoe : Leather → product → material.
• Table : Wood → product → material.
• Jewellery : Gold → product → material.
• Iron : Axe → material → product (reversed).

Concept / Approach:
Normalize direction to “product → material,” then spot the inverted mapping.

Step-by-Step Solution:

Verification / Alternative check:
Rewriting B as “Axe : Iron” would align it to the majority pattern.

Why Other Options Are Wrong:
They consistently express the same direction of relation.

Common Pitfalls:
Overthinking “possible materials”; direction, not exclusivity, is the test cue.

Final Answer:
Iron : Axe