Question: What does the IE FeatureSetEUTRA-DownlinkId identify in E-UTRA?
Option 1: A downlink feature set in E-UTRA list.
Option 2: An uplink feature set in E-UTRA list.
Option 3: A carrier band combination in E-UTRA.
Option 4: A UE's supported band in E-UTRA.
Explanation: The IE FeatureSetEUTRA-DownlinkId is used to identify a downlink feature set in the E-UTRA list, as specified in TS 36.331. This information element helps in identifying the specific features supported by the UE in the downlink direction.