Final answer:
Contracting with insurance companies is not typically a characteristic of HMO plans; instead, HMOs provide healthcare directly to subscribers and include services like outpatient care, free checkups, and early treatment.
Step-by-step explanation:
The question asks which of the following is NOT a characteristic or a service of a Health Maintenance Organization (HMO) plan. Among the options provided, contracting with insurance companies is not typically a characteristic of HMO plans. HMOs themselves provide health plans directly to subscribers, and while they may interact with insurance companies in various ways, contracting as a general characteristic is not accurate. Instead, HMOs focus on providing a range of services such as care on an outpatient basis, free annual checkups, and encouraging early treatment as part of their healthcare model. HMO plans operate by receiving a fixed amount per person enrolled and focusing on preventative care to manage costs.