Question: What does the "facility rejected" cause indicate in a mobile radio interface?
Option 1: The network has accepted the user's request for a specific facility.
Option 2: The user has cancelled their request for a specific facility.
Option 3: The network is currently busy and cannot process the user's request.
Option 4: The network is unable to provide the facility requested by the user.
Explanation: The "facility rejected" cause indicates that the network cannot provide the facility requested by the user, which may be due to various reasons such as lack of resources or compatibility issues. This cause is used to inform the user that their request for a specific facility has been rejected by the network.