When configuring the BGP, if such a warning is generated: " BGPI6ESTABLISHED:OID[oid] The BGP FSM enters the Establishedstate”, which of the following description is true?

When configuring the BGP, if such a warning is generated: " BGPI6ESTABLISHED:OID[oid] The BGP FSM enters the Establishedstate”, which of the following description is true?
A . Indicates that the BGP neighbor has been established
B . The warning message is abnormal and must be dealt with
C . Explain that this type of alarm is generated due to TCP problems
D . Explain that there is a problem due to OPEN message negotiation between BGP neighbors

Answer: A