Why should iBGP sessions be fully meshed within a Transit AS?

A.
A full mesh allows for optimal routing within the Transit AS.

B.
Routes learned viaiBGP are never propagated to other iBGP peers.

C.
Routes learned viaiBGP are never propagated to other eBGP peers.

D.
Routes learned viaeBGP are never propagated to other iBGP peers.

E.
BGP requires redundant TCP sessions betweeniBGP peers.