What technique should be used on BGP edge routers to prevent a multi - homed autonomous system from becoming a trans it system?（）

Advertise with a high MED value all networks that are discovered via external BG
B. Set the no - export community attribute on all networks that are advertised externally.
C. Remove the AS - Path information on all routes in the BGP table pr ior to advertising externally.
D. Set the origin code to incomplete for all networks that are discovered via external BG
E. Only advertise networks externally if they have been discovered via internal BG
F. Use an outgoing distribution list to filte r all networks not originating from inside the autonomous system.