What type of expenses are typically covered by a copayment?

Copayments are a predetermined fixed amount that individuals pay for specific medical services or prescriptions at the time of receiving care. This structure is designed to help share the costs between the insurance provider and the insured individual. Typically, the services that require a copayment include doctor's office visits, specialist consultations, and certain prescriptions. This makes it clear that option C accurately describes the nature of copayments, as they apply to specific services rendered during a visit to a healthcare provider.

In contrast, the other options do not correctly represent the function of copayments. Annual insurance fees are premiums paid for the insurance policy itself and are not directly associated with specific medical services or visits. Furthermore, the phrase "all medical expenses without limit" does not align with how copayments work, as they are not applicable to every expense, but only to particular services listed in the insurance plan. Lastly, copayments do not apply to expenses incurred before the deductible is met, as these costs are usually borne entirely by the insured until the deductible threshold is reached, after which copayments and other cost-sharing mechanisms come into play.