Select the most appropriate antonym of the given word.
DUPLICITOUS

The correct answer is Candid.

Understanding the Given Word:
Duplicitous means deceitful, double-dealing, dishonest, or deliberate in deception (behaving in a way that hides one's true feelings, intentions, or character).

Analyzing the Options:
1. Betraying: Unfaithful, disloyal, or revealing secrets deceitfully. This is similar in meaning (synonymous) to duplicitous.
2. Deceitful: Guilty of or involving deceit; misleading others. This is a direct synonym of duplicitous.
3. Candid: Truthful, straightforward, frank, and honest. This is the exact opposite (antonym) of being duplicitous.
4. Treacherous: Guilty of or involving betrayal or deception; dangerous or untrustworthy. This is also synonymous with duplicitous.

Since we are looking for the antonym (opposite in meaning) of "DUPLICITOUS", the correct choice is Candid.