Verification of truth — Essential part of a shoe A shoe always has ________.

Introduction / Context:
Shoes vary widely, but the core function is to protect/support the foot while walking. Which component is indispensable?

Given Data / Assumptions:

• Shoes can be slip-ons, sandals, loafers, boots, etc.
• Materials and fasteners may vary.

Concept / Approach:
Find the structural part without which a shoe ceases to function as a shoe.

Step-by-Step Solution:
The sole provides the interface with the ground and is essential.Laces are common but not universal (slip-ons/sandals).Leather is a material option; many shoes are synthetic or fabric.“Design” is abstract and always present in some sense, but in these puzzles we prioritize concrete parts; the sole is the accepted invariant.

Final Answer:
Sole