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. Assertiveness training.
• B. Sensate focusing.
• C. Exposure and response prevention.
• D. Systematic desensitization.