The word "captivating" means to hold one's attention in a delightful or enchanting way. To find the best antonym (opposite) for "captivating," we should look for a word that means repulsive or unpleasant.

Options 1, 2, and 4 all suggest negative emotions, but the word "repulsive" (Option 3) most directly conveys the opposite of "captivating." "Repulsive" means causing intense disgust or aversion, which contrasts with the enchanting and delightful qualities of something that is "captivating."

So, Option 3, "Repulsive," is the best antonym.