Final answer:
Jeff is using the self-management strategy of contingency contracting by making an agreement with his roommate regarding his smoking behavior.
Step-by-step explanation:
Jeff is using the self-management strategy of contingency contracting.
Contingency contracting involves creating an agreement between oneself and another person that outlines specific goals and consequences. In this case, Jeff has made an agreement with his roommate regarding his smoking behavior.
This strategy can be effective in promoting behavior change and providing accountability and motivation to meet the agreed-upon goal.