Classification – Odd one out (hand tools/process vs weapon/effect): Find the odd pair: Needle : Prick, Gun : fire, Auger : Bore, Chisel : Carve.

Introduction / Context:
Tool–action pairings typically involve implements used for constructive, medical, or craft processes. Three of the pairs involve hand tools used for controlled, non-combat operations (medical pricking, boring holes, carving). One pair involves a weapon and an act of firing, which is categorically different in purpose and context.

Given Data / Assumptions:

• Needle : Prick → medical/hand tool causing a controlled puncture.
• Auger : Bore → carpentry/earth tool used to drill holes.
• Chisel : Carve → craft/stone/wood tool used to carve or shape material.
• Gun : fire → weapon discharging projectiles.

Concept / Approach:
Group hand-tool/process pairs against a weapon/action pair. The weapon-based pair is the outlier by function and domain (combat vs craft/medical).

Step-by-Step Solution:
Needle ↔ controlled medical/craft effect.Auger ↔ constructive boring action.Chisel ↔ constructive carving action.Gun ↔ combat/weapon firing (non-constructive).

Verification / Alternative check:
Grammar (noun:verb) is consistent across all four and therefore not discriminative; domain/purpose is the decisive factor.

Why Other Options Are Wrong:

• Needle:Prick, Auger:Bore, Chisel:Carve are all tool–operation pairs in productive/medical contexts.

Common Pitfalls:
Assuming “needle:prick” is an “effect” rather than an “action”; in practical usage, pricking is the action performed with the needle, just like boring and carving.

Final Answer:
Gun : fire