question: What is the purpose of the feature 'Multi-server bearer coordination' for MBMS usage in MC services? [3GPP Release 15] option 1: Allowing a single MC service server to manage all MBMS media transmission option 2: Activating an MBMS bearer and notifying relevant events option 3: Application layer FEC to recover packet losses option 4: Applying header compression over MBMS transmissions option 5: Supporting multiple security domains 