The correct option is D deceptive
Candid means truthful and straightforward; frank. The opposite of candid is deceptive, or giving an appearance or impression different from the true one; misleading. Hence, Option D is correct. Among the rest of the options, rude means offensively impolite or bad-mannered, cunning means having or showing skill in achieving one's ends by deceit or evasion, vague means of uncertain, indefinite, or unclear character or meaning. These options do not express this antonym, hence incorrect.