medigap is for A/B, medicare C 你可以買覆蓋低的和A/B一樣的，或者買覆蓋更好的

Your choice

Medicare A+B   OR　Medicare C  basic plan (both pays 80% only, no out of pokcet maximum)

A+B + medigap  OR Medicare C, expensive plan that covers on top of A/B.