Mark is angry when the teacher blames him for misbehaving when it actually was the child behind him who had been acting up. As he leaves after school, he shoves another boy who gets in his way. Freud would say that Mark is unconsciously using the defense mechanism of:

Displacement

Explanation:

Displaced is a defense mechanism. defense mechanism was given Sigmund Freud. it is a defense mechanism in which negative feelings are transferred from real target to the less threatening target. The negative emotions elicited towards the source of feelings rather than threatening a person or subject.

Displacement of aggression is a classical example of displacement of aggression on another person. It is happened a person feels angry due to some outsource comes and displaced his anger on her spouse, then the female will displace her anger children. This is the classic example of displacement defense mechanism. Displacement is a source of reducing anxiety and restoring balance.

Answer: Defense mechanism of displacement

Explanation:

In Freudian school of thoughts, displacement is considered as an defense mechanism (unconscious) under which the brain substitutes a aim or a objective felt in its original state to be either dangerous or not accountable. The term associating with Freud, displacement tends to operate in unconscious mind, the transference of wishes, ideas, or emotions being used to alleviate anxiety.