ACL 2001 defined as 'ipip-prefix 1 permit 10.1.0.0 16' permits the prefix 10.1.0.0 with a subnet mask of /16. This means the correct route entries should match the prefix 10.1.0.0/16. Option D entails prefixes that align logically with this rule - '1.2.0.0/16,1.2.4.0/24,1.2.6.0/24,1.2.8.0/24', where the prefix 1.2.0.0/16 represents a broader range that can include several more specific prefixes such as 1.2.4.0/24, 1.2.6.0/24, and 1.2.8.0/24.