Question: Upon receiving a Floor Idle message from the floor control server interface, what action(s) does the floor participant interface toward the MCPTT client take if the first bit in the subtype of the Floor Idle message requires acknowledgement?
Option 1: Sends the Floor Idle message to the MCPTT floor participant and transitions to 'P: has permission' state.
Option 2: Sends the Floor Idle message to the MCPTT floor participant, stores an indication that a Floor Ack message is expected, and remains in the 'P: has no permission' state.
Option 3: Only sends the Floor Idle message to the MCPTT floor participant without any further actions or state changes.
Option 4: Immediately sends a Floor Ack message back to the floor control server interface without forwarding the Floor Idle message.
Explanation: This is correct because, as specified, upon receiving a Floor Idle message with the acknowledgement required bit set, the interface must both forward the message to the MCPTT floor participant and track the need for a subsequent Floor Ack message, all while maintaining its current permission state ('P: has no permission').