I found his crude manners abominable.

A. flattering

B. sloppy

C. detestable

D. attractive

Answer: Option C

Solution(By Examveda Team)

Flattering : full of praise and compliments.
Sloppy : careless and unsystematic; excessively casual.
Detestable : deserving intense dislike.
Attractive : pleasing or appealing to the senses.
Abominable : causing moral revulsion.

Synonym of Abominable is Detestable