Medicare Part C is not a separate benefit. Part C is the part of Medicare policy that allows Private Health Insurance Companies to provide Medicare benefits. These Medicare private health plans, such as HMOs and PPOs, are known as Medicare Advantage Plans. If you want, you can choose to get your Medicare coverage through a Medicare Advantage Plan instead of through Original Medicare.
IMedicare Advantage Plans must offer at least the same benefits as Original Medicare (those covered under Parts A and B) but can do so with different rules, costs, and coverage restrictions. You also typically get Part D (Prescription Drugs) as part of your Medicare Advantage benefits package. Many different kinds of Medicare Advantage Plans are available. You may pay a monthly premium for this coverage, in addition to your Part B premium.