Ben often acts so daring and overly confident that few people realize he is actually riddled with unconscious insecurity and self-doubt. Ben best illustrates the use of a defense mechanism known as a. regression. b. projection. c. displacement. d. reaction formation.

d. reaction formation.

Explanation:

Reaction formation: In psychology, the term "reaction formation" is described as one of the defense mechanism which is considered as one of the different parts of the psychoanalytic theory and was introduced by Sigmund Freud.

Reaction formation is referred to as a process through which an individual tends to perceives his or her true or genuine desires or feelings to be legally or socially acceptable and therefore he or she attempts to convince oneself and other persons that the opposite of a particular thing is true.

In the question above, Ben best illustrates the use of reaction formation.