Fill in the blank with the most appropriate word.
Where _____ you going tonight?
A verb is used to express an occurrence, action, or state. It is the grammatical centre of the predicate in a sentence.
An auxiliary verb is a verb which gives is used in the formation of tenses, moods, tones, etc.
Option D is correct as the subject is you and the present continuous is used for a present action over a period of time.
The other options are wrong as the subject is you and going indicates continuous tense.
The correct answer is D)are