Question

You think you are smart, Question tag?

Answer 1

you think you are smart, don't you?

Answer 2

Ans.

Question tags are used when you want to attach a question at the end of a simple sentence.

It's a grammatical arrangement in which an imperative or a declarative statement is twisted into the interrogative fragment.

Question tag changes the sentence into a question.

So in this sentence, the answer will be - You think you are smart, don't you?