Consider a Go-Back-N protocol with a sender window size of 4…

Consider a Go-Back-N protocol with a sender window size of 4, a sequence number range of 32 and a message of 100 packets that needs to be sent. Suppose that the sender at some point in time has a window of packets with sequence numbers 6, 7, 8, and 9 and gets an ack labeled 8. Then the sender should: