Two neighboring nodes (A and B) use a sliding-window go-back-N for error control with a 3 -bit sequence number. The window size is 4 . Assuming A is the sender and B is the receiver, show the window positions at A or the following situations. a. Before A sends any frames. (5p) b. After A sends frames 0,1,2 and receives RR 2 from B. (5 p) c. Later, after A sends frames 3,4 , and 5 and receives RR5 from B. (5 p)