Final answer:
John's act of intentionally billing a different treatment to gain financial benefit is an example of fraud.
Step-by-step explanation:
John's act of intentionally billing a unit of therapeutic exercise instead of a hot pack treatment to gain financial benefit, knowing that Medicare does not reimburse for hot packs, is an example of fraud. Fraud involves intentionally deceiving or misrepresenting information for personal gain. In this case, John deliberately misrepresented the treatment provided in order to receive reimbursement.