Final answer:
Medicare Part D covers prescription drugs, and Mrs. Geisler should review changes in premiums, formulary, and cost-sharing during the annual enrollment period to ensure her plan remains suitable.
Step-by-step explanation:
Mrs. Geisler's neighbor is referring to Medicare Part D, which covers prescription drugs. It's important for her to review her Part D options during the annual enrollment period because there can be changes from year to year in factors such as premiums, the list of covered drugs (formulary), and cost-sharing requirements. Since Medicare Part D was introduced as a crucial benefit for the elderly and disabled to help with prescription drug costs, it's beneficial for Mrs. Geisler to stay informed about any updates to ensure her coverage meets her needs and remains cost-effective.