The character is a minor character that has specific traits opposed to the protagonist.
O secondary
third-person
O antagonistic
foil

dramatic irony occurs when the reader/audience knows more about a character's situation than the character does. the one main effect is that it gives the reader a sense of superiority, or detached superiority. the reader not only seemingly discovers what is revealed, but feels superior for doing so.

i don't know sorry i cannot read a novel in 30 min.

explanation:

but just in case i think the answer is b.