Question: When can the Information Element (IE) for uplink data status be included by the Mobile Station (MS)?
Option 1: When the Service Type is set to "voice".
Option 2: When the Service Type is set to "data".
Option 3: When the MS is in idle mode.
Option 4: When the MS is in a handover procedure.
Explanation: The IE for uplink data status can be included by the MS when the Service Type is set to "data", as specified in the Mobile radio interface Layer 3 specification. This indicates that the MS has data to send and is requesting resources from the network.