Professor Bob Has an Incredibly Messy Office, and Really Wants

Professor Bob has an incredibly messy office, and really wants to change but just can't.Professor Bob just read his first book about behavioral economics.To help him keep his office more neat, Professor Bob could hire

A) an expensive office consultant to set up an organizational scheme.Because the consultant's visit was so expensive, Professor Bob will not want to lose his investment.
B) a very expensive custodial service that will clean and bill Professor Bob only when his office needs cleaning.
C) somebody to clean his office once a week for the entire year whether it needs it or not.
D) a sarcastic graduate student to make fun of him when his office becomes messy.
E) All of the above would be equally effective in changing Professor Bob's behavior.