Fill in the blank with the most appropriate word.
Many birds _____ south every winter.
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 A is correct as the sentence is a general statement. Therefore, simple present tense can only be used in the given sentence.
The other options are wrong as no other tense other than simple present can be used.
The correct answer is A)fly