Final answer:
The maximum amount a provider who does not accept assignment from Medicare can charge a patient is 115% of the Medicare-approved amount.
Step-by-step explanation:
When a provider does not accept assignment from Medicare, the most that can be charged to the patient is 115% of the Medicare-approved amount. Therefore, the correct answer to the question is c. 115. Providers who do not accept assignment may charge more than the Medicare-approved amount, but not more than 115% of it. It's important for patients to know if a provider accepts Medicare assignments to avoid unexpected medical costs.