Question: For which type of User Equipment (UE) is it mandatory to support measurement reporting triggered based on a number of cells?
Option 1: UE with Voice over LTE (VoLTE) subscription
Option 2: UE with Aerial UE subscription
Option 3: UE with Machine-Type Communications (MTC) subscription
Option 4: UE with High-Speed Packet Access (HSPA) subscription
Explanation: This is correct because UEs with an Aerial UE subscription are mandated to support measurement reporting triggered by a number of cells, ensuring seamless and efficient network operation for aerial UEs with unique service requirements.