Classification — human anatomy: identify the single option that is NOT itself a distinct sense organ.

Introduction / Context:
Biological classification often hinges on functional roles. Three items are canonical sense organs; one is an anatomical region that contains other parts but is not, itself, a distinct sense organ.

Given Data / Assumptions:

• Tongue → organ for taste.
• Nose → organ for smell (olfaction).
• Eye → organ for vision.
• Mouth → cavity/region containing tongue/teeth; not a single sense organ.

Concept / Approach:
Identify which item names a sense organ in its own right versus a larger anatomical area.

Step-by-Step Solution:
1) Tongue/Nose/Eye → each directly supports one of the five senses.2) Mouth → broader structure (oral cavity) housing parts; not a distinct sense organ.3) Therefore “Mouth” is the outlier.

Verification / Alternative check:
Associate each with a specific sense: taste, smell, sight; “mouth” lacks a unique, dedicated sensory modality.

Why Other Options Are Wrong:
They are each primary organs for a human sense.

Common Pitfalls:
Conflating mouth with tongue; only the tongue is the sense organ (taste buds).

Final Answer:
Mouth