Which one of the statements describes the relationship between BGP and AS correctly?
A. BGP only runs between ASs, and cannot run within an AS.
B. BGP is an EGP running between ASs, and IGP runs within an AS such as OSPF,RIP and IS-IS.
C. BGP builds up network topology by exchanging link-state information among Ass.
D. BGP cannot run between Ass.