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)repel is correct as the word repel means drive or force (an attack or attacker) back or awayand the word captivate means attract and hold the interest and attention of; charm.
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.