Option 1: Abhorent -> Means causing disgust or hatred; both words describe something extremely distasteful or offensive.
Option 2: Alluring -> Means attractive or charming; this is actually the opposite of repugnant.
Option 3: Mandatory -> Means required or compulsory; unrelated to the meaning of repugnant.
Option 4: Remorseful -> Means feeling regret or guilt; doesn't relate to something being disgusting or offensive.
Hence, Option 1: Abhorent -> Both "repugnant" and "abhorrent" describe something that provokes strong feelings of disgust, aversion, or hatred, making them synonyms -> correct