Which of the following is NOT one of the four main types of health insurance plans?

The choice of Health Savings Account (HSA) as the answer is accurate because an HSA is not a type of health insurance plan. Instead, it is a tax-advantaged savings account specifically designed to help individuals save for medical expenses. HSAs can be paired with high-deductible health plans (HDHPs) to allow for tax-free withdrawals for eligible healthcare costs.

In contrast, the other options—Health Maintenance Organization (HMO), Exclusive Provider Organization (EPO), and Preferred Provider Organization (PPO)—are all structured types of health insurance plans that dictate how and where members can access medical care. HMOs typically require members to select a primary care physician and obtain referrals to see specialists; EPOs offer a network of doctors and hospitals but do not cover care outside that network; PPOs provide more flexibility in choosing healthcare providers but typically come with higher costs. Understanding these distinctions helps clarify why HSAs are considered fundamentally different from the other options listed.