Carlo is a minor character, but he provides an interesting contrast to the play’s hero. while the hero is not afraid of dying to defend his principles, carlo is willing to renounce what he believes in order to save his own life. what kind of character is carlo? antagonist protagonist foil

The righr answer is "foil"

A foil character is any character in literature that, through his or her actions and words, highlights and directly contrasts the personal traits, qualities, values, and motivations of another character.  

A foil is a character who contrasts with another character, usually the protagonist, to highlight particular qualities of the other character.

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