Which question should be asked when characterizing the antagonist?
how do others respond to the antagonist?
when is the protagonist introduced?
who is the protagonist?

The question that should be asked when characterizing the antagonist is "How do others respond to the antagonist?" Option A is correct.

An antagonist is the character in a story who is against the protagonist.

The antagonist is opposed to, struggles against, or competes with another; opponent; adversary, in literature, it is the adversary of the hero or protagonist of a drama or other literary work.

The English word antagonist stems from the Greek antagonistēs.

its everything except for telling nonfiction and using first person

is it multiple