Final answer:
d)Repression is considered the most primitive defense mechanism according to Freudian psychological theory, where painful memories or feelings are unconsciously blocked from awareness.
Step-by-step explanation:
The most primitive defense mechanism refers to the one that is least developed and most characteristic of an early stage of development. In psychological theory, particularly as conceived by Sigmund Freud, the most basic defense mechanism is believed to be repression. Repression involves unconsciously blocking out painful or anxiety-inducing memories or feelings from awareness, a process that can lead to symptoms being manifested in various other ways. It serves as a foundation for many other defense mechanisms that involve some form of denial or distortion of reality.