A person without manners or polish

Answer: Option C

One word substitute is Boorish.

Rustic: lacking the sophistication of the city; backward and provincial.
Naive: (of a person or action) showing a lack of experience, wisdom, or judgement.
Boorish: rough and bad-mannered; coarse.
Barbarian: (in ancient times) a member of a people not belonging to one of the great civilizations (Greek, Roman, Christian).