Question: In a Cell Broadcast Service (CBS), what triggers the inclusion of an eNodeB ID in the Broadcast Empty Area List for E-UTRAN?
Option 1: When an eNodeB sends a WRITE-REPLACE WARNING REQUEST to the MME with a Broadcast Completed Area List IE included.
Option 2: When an eNodeB responds to the MME with a WRITE-REPLACE WARNING RESPONSE or KILL RESPONSE without including the respective Broadcast Completed/Canceled Area List IE.
Option 3: Upon receipt of a PWS CANCEL REQUEST from the MME, acknowledging the cancellation of a CBS message.
Option 4: When the MME initiates a new CBS campaign and no eNodeBs have yet responded with area lists.
Explanation: The correct answer is Option 2 because, in the context of Cell Broadcast Service for E-UTRAN, an eNodeB's ID is added to the Broadcast Empty Area List if it responds to the MME with specific messages (WRITE-REPLACE WARNING RESPONSE or KILL RESPONSE) lacking the respective area list IEs, indicating no completed or canceled broadcast areas, thus aiding in managing and tracking the broadcast's reach across network nodes.