The correct option is A polite
The word 'brash' refers to being self-bearing in a rude, noisy or overbearing way.
Option A, polite refers to being respectful and considerate of other people.
Option B, arrogant refers to being full of oneself and boastful.
Option C, kind refers to having a friendly and considerate nature.
Option D, handsome refers to being good-looking.
Thus, according to the meaning, the word 'polite' is the opposite of the word 'brash'.