Which solution allows overlay VNs to communicate with each other in an SD-WAN Architecture?

Which solution allows overlay VNs to communicate with each other in an SD-WAN Architecture?

A. External fusion routers can be used to map VNs to VRFs and selectively route traffic between VRFs. B. GRE tunneling can be configured between fabric edges to connect one VN to another. C. SGTs can be used to permit traffic from one VN to another. D. Route leaking can be used on the fabric border nodes to inject routes from one VN to another.