The teacher felt nettled at the rowdiness of the boys.

Answer: Option B

Pleased : feeling or showing pleasure and satisfaction, especially at an event or a situation.
Annoyed : slightly angry; irritated.
Disgusted : feeling or expressing revulsion or strong disapproval.
Perplexed : completely baffled; very puzzled.
Nettled : irritate or annoy (someone).

Synonym of Nettled is Annoyed