This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Psychiatry
Which of the following excludes painful stimuli from awareness - 
Select and explain. 
A. Repression, B. Reaction formation, C. Projection, D. Rationalization
A: Repression
Answer: A: Repression 
Explanation: Traumatic events (or painful stimuli) are repressed (forced down) in to unconsciousness, i.e. repression acts unconsciously to exclude anxiety provoking ideas or feeling from conscious awareness.