What is defined as a company that provides health care services to enrolled members in exchange for a fixed premium?

A health maintenance organization (HMO) is defined as a company that provides health care services to enrolled members in exchange for a fixed premium. This model emphasizes preventative care and requires members to choose a primary care physician (PCP) who coordinates their health care needs. Members typically must receive services from providers within the HMO's network, and this structured approach often leads to lower out-of-pocket costs for participants compared to other health insurance models.

In contrast, a preferred provider organization (PPO) allows greater flexibility in selecting health care providers but often involves higher costs for members when they seek care outside the network. An insurance carrier is a broad term that refers to any company that provides insurance coverage, but it doesn't specifically describe the structure of providing care like HMOs do. A healthcare alliance refers to a coalition or partnership of various health care organizations working together but doesn't specifically denote a type of company that provides health care services in exchange for a fixed premium. These distinctions highlight why the HMO is correctly identified as the entity that fits the description given in the question.