Question: Upon receiving a Floor Revoke message from the floor control server interface, what actions does the floor participant interface toward the MCPTT client take if the first bit in the subtype of the Floor Revoke message requires acknowledgement?
Option 1: It only sends the Floor Revoke message to the MCPTT floor participant and changes state to 'P: no permission'.
Option 2: It sends the Floor Revoke message to the MCPTT floor participant but does not store any indication regarding a response.
Option 3: It ignores the message if the first bit in the subtype is set, remaining in the 'P: has permission' state without further action.
Option 4: It sends the Floor Revoke message to the MCPTT floor participant and stores an indication that a Floor Ack message to the Floor Revoke message is expected, while remaining in the 'P: has permission' state.
Explanation: This correct answer reflects the detailed protocol behavior specified for handling Floor Revoke messages when acknowledgement is required. By sending the message to the MCPTT floor participant, storing an expectation for a Floor Ack message, and maintaining the 'P: has permission' state, the interface adheres to the nuanced interworking requirements between MCPTT and LMR systems, ensuring proper communication flow and state management.