Fill in the blank with the most appropriate word.
How many languages _______ your mother speak?
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 C is correct as the subject is singular (your mother) and the sentence talks about something general (present tense).
The other options are wrong as speak indicates present tense and how indicates the use of do as an auxiliary verb here.
The correct answer is C)does