Two neighboring nodes (A and B) use a sliding-window protocol with a 3-bit sequence number. As the ARQ mechanism, go-back-N is used with a window size of 4. Assuming A is transmitting and B is receiving, show the window positions for the following succession of events:

a. Before A sends any frames

b. After A sends frames 0, 1, 2 and receives acknowledgment from B for 0 and 1

c. After A sends frames 3, 4, and 5 and B acknowledges 4 and the ACK is received by A