Out of the four alternatives, choose the one which best expresses the opposite meaning of the given word.
Arcanum
The word 'arcanum' means 'hidden or concealed'. The meanings of the words are as follows:
Cogent ⇒ Convincing
Insatiable ⇒ Impossible to satisfy$
Revealed ⇒ Disclosed
Vitriolic ⇒ Corrosive
Thus, option 3 is the correct answer.