Answer:
Stereotype
Explanation:
-Foil is a character that is compared with another one to highlight the qualities of the latter.
-Stereotype is a character in which the personality is influenced by cultural types and it tends to be defined by a exaggerated trait.
-Antagonist is a character that is against the protagonist.
-Protagonist is the main character of a story.
According to this, the answer is that the character that is a type of flat character with one exaggerated personality quality is stereotype.
