Classification – Household linens vs furnishings: pick the odd one out. Three are bedding items; one is primarily a window furnishing. Which option does not belong? Options: Mattress, Pillow, Bed sheet, Curtain.

Introduction / Context:
Domestic-item classifications often use functional context. Bedding comprises items used on a bed for sleeping comfort; curtains are window treatments for privacy and light control.

Given Data / Assumptions:

• Mattress: bedding base.
• Pillow: bedding support.
• Bed sheet: bedding cover/linen.
• Curtain: window furnishing.

Concept / Approach:
Group items by the “bed” usage context and separate the one associated with windows.

Step-by-Step Solution:
Step 1: Tag each item as bedding or non-bedding.Step 2: Mattress, Pillow, Bed sheet are bedding.Step 3: Curtain is not bedding; it is the odd one out.

Verification / Alternative check:
Consider typical store categories: bedding vs curtains/drapes are separate sections.

Why Other Options Are Wrong:
Mattress/Pillow/Bed sheet: All are bedding items.

Common Pitfalls:
Avoid grouping by fabric alone; function and placement are key.

Final Answer:
Curtain