Find the odd fruit (citrus vs non-citrus): Choose the option that belongs to a different botanical/culinary group based on primary fruit family characteristics.

Introduction / Context:
Odd one out questions often hinge on a single stable attribute that cleanly separates one choice from the rest. In fruit classification, a reliable separator is the botanical family and fruit type, particularly the citrus group known for segmented hesperidium fruits with characteristic acidic juice vesicles.

Given Data / Assumptions:

• Orange: a citrus fruit, typically classified as a hesperidium, rich in acidic juice vesicles.
• Litchi: a non-citrus drupe with an aril; family Sapindaceae.
• Apple: a non-citrus pome; family Rosaceae.
• Guava: a non-citrus berry type; family Myrtaceae.

Concept / Approach:
Classify by major botanical grouping and fruit morphology. Citrus fruits share rind, pith, and segmented pulp; non-citrus fruits listed belong to different families and morphologies that do not match citrus traits.

Step-by-Step Solution:

Verification / Alternative check:
Check typical culinary profiles: oranges are sour to sweet-tart with segment membranes and a peel with oil glands, unlike the textures and structures of litchi, apple, and guava.

Why Other Options Are Wrong:
Litchi, Apple, and Guava are all non-citrus and do not share the signature rind-pith-segment structure of citrus fruits.

Common Pitfalls:
Do not rely solely on sweetness or color; the decisive factor is the citrus morphology and family.

Final Answer:
Orange