Final answer:
The AARP Medicare Supplement Insurance Plan is the only Medigap plan associated with the AARP name and is insured by UnitedHealthcare Insurance Company.
Step-by-step explanation:
The question is regarding the Medicare Supplement Insurance plans that are endorsed by the AARP organization. These plans are commonly referred to as Medigap and are standardized by the federal government, although insurance companies can decide which plan options they want to offer. The AARP Medicare Supplement Insurance Plan, insured by UnitedHealthcare Insurance Company, is the only Medigap plan that carries the AARP name.