How does Inter-AS Option-A function when two PE routers in different autonomous systems are directly...

The two routers share all Inter-AS VPNv4 routes and redistribute routes within an IBGP session to provide end-to-end reach.

The two routers establish an MP-EBGP session to share their customers' respective VPNv4 routes.

The two routers treat one another as CE routers and advertise unlabeled IPv4 routes through an EBGP session.

The two routers share VPNv4 routes over a multihop EBGP session and set up an Inter-AS tunnel using one another's label.