Classification — common fruits: select the single option that does NOT match the number form of the others.

Introduction / Context:
Sometimes the distinguishing feature is grammatical form rather than category. All four items are fruits, but one is conventionally used in the plural form as a common-count noun in everyday English.

Given Data / Assumptions:

• Orange, Apple, Guava → commonly cited in singular when naming the fruit generically.
• Grapes → typically referenced in plural; a bunch of grapes.

Concept / Approach:
Identify the unique number form or conventional lexicalization (singular vs plural) among otherwise same-category items.

Step-by-Step Solution:
1) Note grammatical number: A–C appear in singular; D is written plural (“Grapes”).2) Category is identical (all fruits), so grammar/usage becomes the discriminator.3) Therefore “Grapes” is the odd item by number form.

Verification / Alternative check:
Try rephrasing with “a/an”: “an orange/an apple/a guava” are natural; “a grapes” is ungrammatical; we would say “a grape” or “grapes”.

Why Other Options Are Wrong:
They share both the category and the singular form, matching each other closely.

Common Pitfalls:
Looking for botanical subtypes; while differences exist, the intended cue here is grammatical convention.

Final Answer:
Grapes