Correct option is A
'Polite' means having good manners, courteous, and respectful behavior towards others.
• The opposite of 'Polite' is 'Rude', which means discourteous, impolite, and disrespectful behavior towards others.
• Antonyms: Rude, impolite, discourteous.
• Synonyms: Courteous, respectful, well-mannered.
Meanings of the given words:
• Civil: relating to ordinary citizens and their concerns, as distinct from military or ecclesiastical matters.
• Decent: conforming with generally accepted standards of respectable or moral behavior.
• Sober: not affected by alcohol; serious, sensible, and solemn.