Which of the following is included in packet radio transmissions?

Packet radio breaks data into individual 'packets' before sending them. Each packet contains a header with routing information, such as the call signs of the sender and the destination, which ensures the packet reaches the correct recipient. Additionally, packet radio utilizes a checksum for error detection. If the receiving station calculates a different checksum than what was sent, it knows an error occurred. The system will then use an Automatic Repeat Request (ARQ) to ask the sender to transmit that specific packet again. Therefore, all the listed features are fundamental components of packet radio transmissions.