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 B)disfigure is correct as the word disfigure means spoil the appearance ofand the word embellish means make (something) more attractive by the addition of decorative details or features.
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.