Which of the following is included in packet radio transmissions?
A checksum that permits error detection
A header that contains the call sign of the station to which the information is being sent
Automatic repeat request in case of error
All these choices are correct✓Correct answer
Explanation
The AX.25 packet frame contains all three: a header with the destination and source call signs for addressing, a frame check sequence that lets the receiver detect corrupted frames, and a protocol that asks for retransmission when a frame fails that check. Since all three are part of the protocol, the combined choice is correct.