Choose the option which is the antonym (opposite) of the word used in the sentence given below:
Although her happiness was manifest in her cheerful demeanor, the hidden sorrow in her eyes revealed a deeper emotional struggle.

The correct antonym is (a) manifest/hidden.
Explanation:
"Manifest" means clear or obvious, while "hidden" means concealed or not visible, making them direct antonyms in this context. The other pairs do not have opposite meanings.
Meanings of all options:
· Manifest: Clear or obvious to the eye or mind.
· Hidden: Kept out of sight; concealed.
· Demeanor: Outward behavior or bearing.
· Sorrow: A feeling of deep distress caused by loss, disappointment, or other misfortune.
· Happiness: The state of being happy.
· Struggle: A forceful or violent effort to get free of restraint or resist attack.
· Revealed: Make (previously unknown or secret information) known to others.