Pick out the correct question tag for the following sentence: You don…

The correct answer is Option (1) → do you?

Question tag:

• A negative statement takes a positive tag, and a positive statement a negative tag.
• The tag repeats the auxiliary of the main clause and uses the subject pronoun.
  • Main clause: You don't know (auxiliary do, negative)
  • "where he went" is only a clause inside the sentence. The tag follows "You don't know".
• Positive tag with "do" and "you": do you?

Why the Other Options are Incorrect?

Option 2: isn't it? — Incorrect. Wrong auxiliary (is for do), wrong pronoun (it for you), and negative after a negative.

Option 3: don't you? — Incorrect. A negative statement cannot take a negative tag.

Option 4: are you? — Incorrect. The verb is "do ... know", so the tag must use do, not are.