Synonyms are words which have the same or nearly the same meaning in the same language.
Antonyms are words which have opposite meaning in comparison to the other.
Option A)stationary is correct as the word stationary means not moving or not intended to be movedand the word fugacious means tending to disappear; fleeting.
Both the words are opposite of each other.
The other options are not correct as they do not have the opposite meaning to the given word.