Question: In a Proximity Services (ProSe) scenario, what is the primary purpose of the 'PC Three Control Protocol Cause' field in relation to messages from the User Equipment (UE)?
Option 1: To indicate the UE's preferred proximity service settings.
Option 2: To specify why a DISCOVERY_REQUEST or Match_Report message from the UE was rejected by the ProSe Function.
Option 3: To notify the UE about available ProSe Functions in the network.
Option 4: To request additional information for proximity-based charging.
Explanation: The correct answer, Option 2, highlights the field's role in conveying the rejection reason for specific messages (DISCOVERY_REQUEST or Match_Report) sent by the UE to the ProSe Function. This is crucial for troubleshooting and managing ProSe services in a telecommunications network, ensuring efficient communication between UEs and the ProSe Function.