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 D)despise is correct as the word despise means feel contempt or a deep repugnance forand the word admire means feel contempt or a deep repugnance fo.
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.