Final answer:
Denial, involves refusing to accept reality or fact, acting as if a painful event, thought, or feeling does not exist. It is considered one of the most primitive of the defense mechanisms because it is characteristic of very early childhood development. The correct answer is option 1.
Step-by-step explanation:
The most primitive defense mechanism is denial, where an individual refuses to accept or acknowledge reality. For example, a person may deny the existence of a problem or refuse to believe a diagnosis of a serious illness. Denial is commonly seen in situations where the truth is too painful or threatening.
Other defense mechanisms mentioned in the question include repression, where anxiety-causing memories are blocked from consciousness, and displacement, where an individual redirects their emotions or impulses from an original target to a substitute target. A person might, for instance, take out their frustration on someone or something unrelated to the source of their anger.