Which three conditions can cause BGP n eighbor establishment to fail?（）

• A、The IBGP neighbor is not directly connected.
• B、BGP synchronization is enabled in a transit autonomous system with fully - meshed IBGP neighbors.
• C、The EBGP neighbor ebgp - multihop option is set to the de fault value.
• D、The BGP update interval is different between the two BGP neighbors.
• E、The BGP neighbor is referencing an incorrect autonomous system number in its neighbor statement.
• F、There is an access list blocking all TCP traffic between the two  BGP neighbors.