Your MPLS implementation is currently using internal backdoor links. What can you do to minimize the impact of having these links？（）
- A use BGP as the CE-PE routing protocol
- B use OSPF as the CE-PE routing protocol
- C use EIGRP as the CE-PE routing protocol
- D use the SP to redistribute routes as external routes for OSPF and EIGRP
- E use route redistribution at each location to ensure external routes are imported into the IGP