What is a co-pay in the context of health insurance?

A co-pay is best defined as the amount of money that a patient is required to pay out of pocket for a specific medical service, with the insurance company covering the remainder of the costs. This payment is often a fixed amount and applies to various services, such as doctor visits, emergency room visits, or prescriptions. The co-pay structure helps to share the financial responsibility of healthcare costs between the patient and the insurance provider.

In this context, it helps to clarify how this amount works within the broader framework of health insurance. The other answer choices reflect different aspects of health insurance but do not accurately describe a co-pay. For instance, the total cost of a medical service encompasses what both the patient and the insurer pay together, rather than just the patient's share. The yearly fee to maintain coverage refers to premiums, which is a separate concept, while the percentage of costs shared between the patient and insurer relates to co-insurance, which differs from the fixed nature of a co-pay. Thus, option B accurately captures the essence of what a co-pay entails.