Find the odd biological item (fruits vs tuber): Pick the one that is not a true fruit but an underground storage organ.

Introduction / Context:
Food items can be classified botanically. Three of the options are true fruits (developed from the ovary and typically enclosing seeds), whereas one is a tuber (a modified underground stem used for storage).

Given Data / Assumptions:

• Apple: fleshy fruit.
• Orange: citrus fruit.
• Guava: fleshy fruit with seeds.
• Potato: tuber (underground stem), vegetative organ, not a fruit.

Concept / Approach:
Use botanical definitions rather than culinary categories. Fruits arise from flowers after fertilization; tubers are modified stems for nutrient storage. That makes potato categorically different from the others.

Step-by-Step Solution:

Verification / Alternative check:
Seeds test: fruits usually contain seeds; a potato tuber does not (eyes are nodes, not seeds).

Why Other Options Are Wrong:
They are all botanical fruits and thus form a coherent group.

Common Pitfalls:
Avoid the “vegetable vs fruit” culinary confusion. The question expects the botanical criterion.

Final Answer:
Potato