Which of the following actions will trigger SgNB release by the MeNB?

The UE inactivity timer on the NR side expiring and the air interface link on the NR side being abnormal, and a UE reporting SCG Failure Info to the eNodeB, can both trigger the MeNB to release the SgNB. Other actions, such as an inter-SgNB cell change or the MeNB detecting an abnormal X2 link, may also lead to SgNB release, but are not the trigger for it.

Extended Cyclic Prefix - an overview | ScienceDirect Topics

https://www.sciencedirect.com/topics/engineering/extended-cyclic-prefix

5G NR Numerology - Subcarrier Spcaing (SCS) - Techplayon

http://www.techplayon.com/5g-nr-numerology-subcarrier-spcaing-scs/