Consider a source and destination pair connected by a network path of capacity 10 Mbps and an average round-trip time of 50 ms (measured from when the source transmits the first bit of a packet until the destination's ack is received). Assume a packet size of 1000 bytes, and that the loss probability is negligibly small. (a) Give the maximum achievable data transfer rate in Mbps, assuming use of the stop- and-wait reliable data transfer protocol. (b) Give the maximum achievable data transfer rate in Mbps, assuming use of a sliding window reliable data transfer protocol with maximum sending window sizes of 10 and 50. (c) Assuming again use of a sliding window protocol, how big would the maximum sending window have to be to ensure that, when all packets and acks are received correctly, the source would never have to pause its transmissions to wait for an ack to be returned? (d) Under what circumstances, given these values for capacity, round-trip time, and packet size, could it be beneficial to have a maximum sending window size larger than that given in your answer to part (c)?