He is urbane in his manners.

Answer: Option C

Urban : in, relating to, or characteristic of a town or city.
Sensible : done or chosen in accordance with wisdom or prudence; likely to be of benefit.
Civil : courteous and polite.
Sane : (of a person) of sound mind; not mad or mentally ill.
Urbane : (of a person, especially a man) courteous and refined in manner.

Synonym of Urbane is Civil