In terms of Medicare Supplement Insurance Plans, what is adjusted when Medicare adjusts its cost-sharing amounts?

The assertion that benefit amounts are automatically updated in response to changes in Medicare's cost-sharing amounts is correct. Medicare Supplement Insurance Plans, also known as Medigap plans, are designed to fill the coverage gaps left by Medicare. As Medicare adjusts its cost-sharing policies, such as deductibles, copayments, or coinsurance, the benefits provided by Medigap plans are typically standardized according to specific plan types. This means that as Medicare's costs change, the benefits that these supplemental plans provide may also be adjusted to reflect those changes, ensuring that policyholders continue to have appropriate coverage.

This automatic update is crucial for maintaining the relevance and effectiveness of Medigap policies, allowing beneficiaries to effectively manage their healthcare expenses alongside Medicare's adjustments. The other options suggest changes in premiums, enrollment periods, or plan adaptability, but these do not typically align with the defined purpose and operational framework of Medicare Supplement plans.