Question: What MIME type should be used for the keep-updated XML fragment sent in the body of the HTTP POST request during MBMS (Multimedia Broadcast/Multicast Service) registration?
Option 1: application/vnd.3gpp.keep-updated+xml
Option 2: text/xml; charset=utf-8
Option 3: application/http; msgtype=request
Option 4: multipart/form-data; boundary=keep_updated
Explanation: In the context of MBMS registration, specifically for keep-updated services, using the correct MIME type is crucial for proper communication between the UE (User Equipment) and the BM-SC (Broadcast Multicast Service Center). The specified MIME type `application/vnd.3gpp.keep-updated+xml` identifies the XML fragment's purpose and format accurately, ensuring the BM-SC can process the request correctly, aligning with HTTP request principles for specialized services.