Final answer:
Insurance claims for a patient with Medicare and Medigap should initially be sent to Medicare. After Medicare's coverage, the claim can be forwarded to the Medigap provider.
Step-by-step explanation:
When filing an insurance claim for Michelle Columbus, who has Medicare and a Medigap insurance policy, the claim should first be sent to Medicare. After Medicare processes the claim and pays its share, the remaining charges can then be sent to the Medigap insurance provider for consideration of additional payment, per the terms of the supplemental policy.
This is because Medigap, also known as Medicare Supplement Insurance, is designed to cover certain out-of-pocket costs not covered by original Medicare, such as deductibles, coinsurance, and copayments.
In answering the multiple-choice question provided, the healthcare system that primarily offers insurance to those over sixty-five years old is Medicare, as indicated in option (b).