Synonym of CANDID

Answer: Option C

Sincere : free from pretence or deceit; proceeding from genuine feelings.
Polite : having or showing behaviour that is respectful and considerate of other people.
Plain-spoken : outspoken or blunt; candid.
Rude : offensively impolite or bad-mannered.
Candid : truthful and straightforward; frank.

Synonym of Candid is Plain-spoken