Question: What action does the MAC entity take when it receives an SCI on the PSCCH for sidelink communication with a Group Destination ID of interest?
Option 1: It discards the SCI and associated HARQ information.
Option 2: It determines the set of subframes in which reception of the first transport blocks occur, stores the SCI and associated HARQ information, and delivers them to the Sidelink HARQ Entity.
Option 3: It only stores the SCI and associated HARQ information without determining the set of subframes for reception of the first transport blocks.
Option 4: It ignores the SCI and does not take any further action.
Explanation: According to the MAC protocol specification, when the MAC entity receives an SCI on the PSCCH for sidelink communication with a Group Destination ID of interest, it determines the set of subframes in which reception of the first transport blocks occur, stores the SCI and associated HARQ information as valid for those subframes, and delivers them to the Sidelink HARQ Entity. This ensures that the MAC entity can properly manage the sidelink communication and handle any potential errors or retransmissions.