This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Psychoanalysis, 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: Repression is the defense mechanism which removes painful memories or unacceptable desires away from the consciousness or awareness.