Which of the Following Best Defines a Defense Mechanism

Which of the following best defines a defense mechanism?

A) an attempt to manage conflict between the id and superego
B) the client's unconscious tendency to interact with the therapist as if the therapist were very similar to an important person in the client's personal history (mother or father, for example)
C) a verbal or behavioral "mistake" that, according to psychodynamic psychotherapists, communicates an underlying unconscious wish
D) an attempt to say whatever comes to mind, without censorship, no matter how nonsensical, illogical, or inappropriate