Correct Answer: Uncandid

Solution : The correct answer is the third option.

The word that is opposite in meaning to forthright is uncandid .

The term "forthright" describes someone as direct, honest, and straightforward in his or her speech or actions. On the contrary, the word "uncandid" refers to someone who is not sincere, open, or straightforward.

The meanings of the other options are as follows:

The adjective artless describes someone or something as sincere, straightforward, and without deception.

The adjective uninhibited describes someone or something as free and unconstrained, often without inhibitions or restraints.

The adjective blunt describes someone or something as direct, sometimes to the point of being rude or lacking subtlety.

Therefore, the correct answer is uncandid.