Final answer:
Medigap Plan HMO is a type of insurance that requires enrollees to use a network of providers in order to receive full benefits.
Step-by-step explanation:
The type of Medigap insurance that requires enrollees to use a network of providers in order to receive full benefits is Medigap Plan HMO. Medigap, also known as Medicare Supplement Insurance, is private insurance that helps cover the costs that Original Medicare doesn't pay. Medigap Plan HMO requires individuals to use doctors and hospitals within their network to receive full coverage and benefits.