Fill in the blank with a suitable modal:
It's very cold. You _________ to put a sweater on.
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 B is correct as the cold indicates the necessity of putting on a sweater.
The other options are wrong as no other modal can be used here.
The correct answer is B)ought