Question: In an MBMS context, what does the presence of the `r12:appService` child element within `userServiceDescription` signify about the associated MBMS User Service?
Option 1: It indicates a purely unicast delivery method for the service.
Option 2: It signifies that the service is exclusively linked to a broadcast application without unicast capabilities.
Option 3: It shows that the MBMS User Service is an application service explicitly linked to both `r12:broadcastAppService` and `r12:unicastAppService` elements under `deliveryMethod`.
Option 4: It implies that the service description does not support multimedia content.
Explanation: The presence of `r12:appService` within `userServiceDescription` indicates an explicit link to both broadcast and unicast application services under the delivery method, highlighting the service's versatility in delivery approaches.