Which two conditions can cause BGP neighbor establishment to fail?

Which two conditions can cause BGP neighbor establishment to fail? (Choose Two)
A. There is an access list blocking all TCP traffic between the two BGP neighbors
B. The IBGP neighbor is not directly connected.
C. BGP synchronization is enabled in a transit autonomous system with fully-meshed IBGP neighbors.
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.