b) Consider two hosts A and B that are quite far apart. They are communicating using Selective Repeat protocol with a window size of 5 and a sequence number space of 4 bits. Assuming A is the source of the data and B is the sink, i.e., this is a one-way data flow, and packets may be lost or corrupted but without reordering. Consider the following (independent) events. i. At present, the senders window at A is at [5,6,7,8,9] and all labels are usable but not yet used. A receives an uncorrupted ACK packet with seq # 4. Is it possible? If so, explain why A may receive an ACK 4 and estimate what are the possible receivers window at B at the time B sent this ACK 4. If not, explain why it is not possible. ii. At present, the senders window at A is at [5,6,7,8,9] and all labels are used, i.e., As window is exhausted. A receives an uncorrupted ACK packet with seq # 4. Is it possible? If so, explain why A may receive an ACK 4 and estimate what are the possible receivers window at B at the time B sent this ACK 4. If not, explain why it is not possible. iii. At present, the receive window at B is at [1,2,3,4,5]. B receives an uncorrupted data packet with seq # 4. Is that possible? If so, what will B, do and estimate what are the possible senders windows at A at this moment? if not, explain why it is not possible. iv. At present, the receive window at B is at [8,9,10,11,12]. B has successfully received packets with seq # 10 and # 11 and has sent ACK 10 and ACK 11 to A. Then B receives an uncorrupted data packet with seq # 13. Is that possible? If so, what will B do, and estimate what are the possible senders windows at A at this moment? If not, explain why it is not possible.