Question: What is the primary purpose of the Serial Number parameter in an ETWS (Earthquake and Tsunami Warning System) Primary Notification message?
Option 1: To uniquely identify the source of the ETWS alert, ensuring differentiation from other warning systems.
Option 2: To indicate the severity level of the emergency situation to the User Equipment (UE).
Option 3: To track changes made to the ETWS Primary Notification message for a given Message Identifier.
Option 4: To specify the geographical area targeted by the warning.
Explanation: The Serial Number parameter identifies when an ETWS Primary Notification message with a specific Message Identifier has been updated or changed, enabling User Equipment (UE) to distinguish between new and previously received versions of the same alert.