A stop and wait link layer protocol uses sequence numbers modulo 4. The following events occur in sequence at the receiver: A frame carrying a data block with sequence number 3 is received correctly, and a response is sent with sequence number 3; A frame is received with errors, and a response is sent with sequence number 3; A frame is received correctly, with the expected data block, and a response is sent Bits are received, but no start marker is found and no response is sent; A frame is received correctly, with the expected data block, and a response is sent A frame is received with errors, and a response is sent with sequence number x; A frame is received correctly, with the expected data block, and a response is sent A frame is received correctly, with the expected data block, and a response is sent A frame is received correctly, with a duplicate data block, and a response is sent with sequence number y Write x and y as a 2-digit number xy (value 10x + y)