An iPhone user receives an 'Unknown Accessory Detected' alert on their phone after leaving an airport lounge. The alert says an item has been traveling with them. What Apple feature generates this alert and what privacy problem does it address?

• A.B. iOS's Bluetooth threat detection system, which identifies unauthorized Bluetooth LE peripherals performing data exfiltration
• B.A. Find My's Unknown Tracker Alerts: it detects AirTags or Find My-enabled accessories that have been separated from their owner's device and are moving with a non-owner, addressing the risk of covert location tracking using AirTags
• C.C. Apple's Lost Mode synchronization alert, which triggers when a missing device is located near your current position
• D.D. The NFC reader detects an NFC chip embedded in luggage that belongs to another passenger