Lee is a high school teacher. He has difficulty grading his students’ papers because he constantly checks and rechecks the students' answers. He fears that he has made a mistake in the calculations. Lee's checking routines are not limited to his students' work. He also checks the locks on his classroom door several times before leaving school, and performs these kinds of rituals at home as well. These procedures are time consuming and cause him considerable distress in his ability to function at work and in his social relationships. Lee is most likely exhibiting: