6988. He was annoyed at his flippant remark.

✅ The correct answer is option A.
Discourteous : showing rudeness and a lack of consideration for other people.

Bitter : having a sharp, pungent taste or smell; not sweet.

Humorous : causing laughter and amusement; comic.

Casual : relaxed and unconcerned.

Flippant : not showing a serious or respectful attitude.

Synonym of Flippant is Discourteous