单项选择题

MeNB站间携带SN的X2切换流程过程,UE检测到满足切换测量门限条件的邻区之后,上报测量报告,然后MN给SN发送哪条消息?()

A.SgNB modification request
B.SgNB release request
C.SgNB release request acknowledge
D.SgNB modification request acknowledge