Select the most appropriate option to substitute the highlighted segment in the given sentence. If there is no need to substitute it, select ‘No substitution’.
You have locked the gate, isn't it?

Correct option is D

The correct substitution of the highlighted words is (d) haven’t you.
Explanation: A question tag is used for confirmation and must match the auxiliary verb and subject of the main sentence. The main sentence is in present perfect (have locked), so the tag should be “haven’t you”.
Grammatical Rule Used:
· Use the opposite polarity in tag (affirmative → negative)
· Repeat the auxiliary verb from the main sentence
· Use personal pronoun as subject in the tag
Example:
You have finished the work, haven’t you?
Information Booster:
· If the main clause is positive, tag must be negative, and vice versa.
· Always use contracted form (isn’t, aren’t, haven’t etc.) in spoken/written tags.