Question: What type of indication is sent to the GMM sublayer in case of a lower layer failure?
Option 1: A request for retransmission
Option 2: A notification of successful transmission
Option 3: An error that cannot be corrected by the lower layers
Option 4: A signal strength measurement report
Explanation: In case of a lower layer failure, the lower layers send an indication to the GMM sublayer that an error has occurred which cannot be corrected by the lower layers. This is typically done to notify the upper layers of the failure so they can take necessary actions.