Correct Answer: Known

Solution : The correct answer is the first option.

The word clandestine means done secretly or kept hidden, whereas known suggests that something is not kept secret or hidden; it is openly recognised or acknowledged. Hence, known is the correct antonym for "clandestine".

The meanings of the other options are as follows.

• Private : While it means not publicly known, it doesn't necessarily imply secrecy. It can refer to something being reserved or not shared with everyone, but it may not be completely hidden.

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• Sneaky : It is a synonym for clandestine, meaning it's not an antonym. It suggests behaving in a secret, sly, or deceitful manner.

• Illicit : It is a synonym for clandestine, indicating something that is forbidden by law, rules, or custom and often done in secret. It's not an antonym in this context.