She is a nice girl ______?
She is a nice girl ______?
Explanation
"She is a nice girl." is a positive statement.
The auxiliary verb here is "is" (from "is a nice girl").
To form the tag question, we invert the auxiliary verb and add the corresponding pronoun.
Thus, the tag question is:
"She is a nice girl, isn't she?"
This structure follows the rule: positive statement + negative tag.
Therefore, the correct answer is: Isn't she