Choose the sentence that uses the correct question tag:

The correct answer is Option (4) → I am the tallest girl in my class, aren’t I?

Question tag after “I am”:

A positive sentence with “I am” takes the negative tag “aren’t I”. This is the one case where “am” changes to “are” in the tag.

Why the Other Options are Incorrect?

Option 1: The postman’s bicycle was stolen yesterday, wasn’t he? — Incorrect. The tag uses the pronoun for the subject. The subject is “bicycle”, not “postman”. So the pronoun is “it”.
Corrected: The postman’s bicycle was stolen yesterday, wasn’t it?

Option 2: Ritu has never been to Goa, hasn’t she? — Incorrect. “Never” makes the sentence negative, even without “not”. A negative sentence takes a positive tag.
Corrected: Ritu has never been to Goa, has she?

Option 3: The vegetable vendors came late today, weren’t they? — Incorrect. The given sentence says “came”. It has no helping verb, so the tag must use “did”, not “were”.
Corrected: The vegetable vendors came late today, didn’t they?