Which of the following is a characteristic of Health Maintenance Organizations (HMOs)?

Health Maintenance Organizations (HMOs) are designed to provide comprehensive health care services to members for a fixed monthly fee, which is a key characteristic of how they operate. This model emphasizes preventive care and wellness, ensuring that members have access to necessary services without additional out-of-pocket costs for each visit. The fixed monthly fee generally includes a wide range of services such as medical visits, hospitalization, and preventive care, all coordinated through a primary care physician.

The structure of HMOs typically encourages enrollees to utilize in-network providers, and they often cover preventive services, which aligns with the focus on maintaining health and preventing illness. This contrasts with other types of insurance models that might require higher premiums or deductibles, or involve complexities like requiring out-of-network referrals for specialist services. Therefore, the characteristic of providing comprehensive care for a fixed monthly fee accurately captures the essence of how HMOs function, making it the correct answer.