题目内容：
BGP runs over a reliable transport （ ）. This eliminates the need to implement explicit update fragmentation, retransmission, acknowledgement, and （ ）. Any authentication scheme used by the transport protocol may be used in addition to BGP's own （请作答此空）mechanisms. The error notification mechanism used in BGP （ ）that the transport protocol supports a “graceful” close, i.e., that all outstanding data will be delivered （ ）the connection is closed.
A.solution
B.authorization
C.authentication
D.auditing
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答案解析：