Classification – Choose the odd one out by focusing on weapon type. Three are firearms that discharge projectiles using explosive force; one is a bladed melee weapon. Which option does not belong? Options: Rifle, Cannon, Sword, Pistol.

Introduction / Context:
In classification questions, grouping by mechanism or mode of action is often decisive. Firearms use propellant-based force to launch projectiles; melee weapons rely on physical contact and cutting or striking. Identifying the distinct mechanism isolates the exception.

Given Data / Assumptions:

• Rifle: firearm (projectile weapon).
• Cannon: firearm/artillery (projectile weapon).
• Pistol: firearm (projectile weapon).
• Sword: melee, bladed weapon.

Concept / Approach:
Group by propulsion mechanism: explosive propellant vs hand-wielded cutting. The single melee weapon among three firearms is the odd one out.

Step-by-Step Solution:
Step 1: Tag each item as firearm or melee.Step 2: Observe that Rifle, Cannon, and Pistol share the firearm mechanism.Step 3: Sword is melee; therefore, it is the exception.

Verification / Alternative check:
Consider distance of engagement: firearms operate at range; swords require close contact—confirming the category difference.

Why Other Options Are Wrong:
Rifle/Cannon/Pistol: All are firearms and thus belong to the main group.

Common Pitfalls:
Avoid grouping by size or era; mechanism of action is the intended criterion.

Final Answer:
Sword