A 25 year old female presents with 2 year history of repetitive, irresistible thoughts of contamination with dirt associated with repetitive hand washing. She reports these thoughts to be her own and distressing; but is not able to overcome them along with medications. She is most likely to benefit from which of the following therapies?
A. Exposure and response prevention
B. Systematic desensitization
C. Assertiveness training
D. Sensate focusing