Which two header fields do a SIP user Agent Server use to indicate that the message needs Provisional Response Acknowledgement? (choose two)
A. Allow: 100rel
B. Cseq:[Numeric value that uniquely identifies the response message]
C. Rack:[Numeric value that uniquely identifies the response message]
D. Require: 100rel
E. Rseq:[Numeric value that uniquely identifies the response message]
F. Allow-Events: 100rel
Correct