Which of these is a Layer 2 transport architecture that provides packet-based transmission optimized for data based on a dual （counter-rotating） ring topology？（）

A. Virtual Gateway
B. Real-IP Gateway
C. NAT Gateway
D. IP-IP Gateway

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