Choose the sentence that uses the correct question tag:

The correct answer is Option (4) → Everyone in the office was invited to the Diwali lunch, weren’t they?

Question tag after “everyone”:

“Everyone” takes a singular verb, like “was”. But in the tag, it becomes “they”. With “they”, “was” changes to “were”. The sentence is positive, so the tag is negative: “weren’t they”.

Why the Other Options are Incorrect?

Option 1: The plumber fixed the leaking pipe, wasn’t he? — Incorrect. The given sentence says “fixed”. It is in the simple past with no helping verb. So the tag must use “did”, not “was”.
Corrected: The plumber fixed the leaking pipe, didn’t he?

Option 2: There isn’t any sugar in the jar, isn’t there? — Incorrect. The sentence has “isn’t”, so it is negative. A negative sentence takes a positive tag.
Corrected: There isn’t any sugar in the jar, is there?

Option 3: The tourists were tired after the long trek, weren’t we? — Incorrect. The tag uses the pronoun for the subject. “The tourists” becomes “they”, not “we”.
Corrected: The tourists were tired after the long trek, weren’t they?