Question: Upon receiving a Floor Release message with Acknowledgment required (first bit in subtype set to '1'), what action does the IWF floor control server take towards the MCPTT client?
Option 1: Send a Floor Taken message with the Granted Party's Identity field.
Option 2: Send a Floor Ack message with Message Type set to '4' (Floor Release) and Source set to '2'.
Option 3: Enter the 'U: not permitted and Floor Idle' state without sending any message.
Option 4: Request the floor again by sending a new Floor Request message.
Explanation: According to the specified behavior for handling a Floor Release message with Acknowledgment required, the IWF floor control server must respond with a Floor Ack message. This message is crucial for confirming the release of the floor, ensuring proper synchronization and state management between the MCPTT client and the server. The correct configuration of the Message Type and Source fields in the Floor Ack message (as described in Option 2) is essential for accurate communication.