Which statement is correct about transit AS and iBGP?

Which statement is correct about transit AS and iBGP?

A.
The iBGP full mesh is a physical full mesh of all the routers within a transit AS.

B.
The iBGP full mesh is a logical mesh of TCP sessions.

C.
Transit AS running full-mesh iBGP requires synchronization to be enabled.

D.
Transit AS running full-mesh iBGP requires next-hop-self to be enabled on all the core routers.

E.
iBGP neighbors within a transit AS must be directly connected to each other.

F.
To prevent routing loops within a transit AS, eBGP updates are not propagated to iBGP peers.