Question: Under what condition is the addition of Secondary Cells (SCells) performed during an RRC connection reconfiguration procedure in E-UTRAN?
Option 1: Always, as part of the initial RRC connection setup
Option 2: Only when AS (Access Stratum) security has been activated
Option 3: When at least one Data Radio Bearer (DRB) is established and not suspended on SRB2
Option 4: Upon UE request during handover to a different eNodeB
Explanation: The correct answer, Option 2, highlights the specific security prerequisite for adding SCells during an RRC connection reconfiguration. This emphasizes the importance of AS security activation in enabling certain RRC procedures, including the addition of SCells, to ensure secure communication in E-UTRAN. Options 1, 3, and 4 are incorrect as they either misrepresent the condition (Option 1), mix conditions applicable to other scenarios (Option 3), or introduce an unrelated trigger (Option 4).