How might an author make a character the antagonist in a story?

Aby making her evil.
Bby having her change during the course of a story.
Cby having her act as a sidekick to the protagonist.
Dby putting her in conflict with the hero.

Verified Answer :

An antagonist means someone who is actively against or opposes someone or something. 
To make a character an antagonist in a story, the most likable choice would be D. By putting her in conflict with the hero. Because that would make them meet against each other face to face to disagree and create a turning point.

d is the apex answer