0,1,2,3,4,5,6,7 now 3 frames are send & every acknowledment get then windowsize decrease
suppose 0,1,2 sent.
0,1,2,3,4,5,6,7 now 0 frame acknowledgement arrive
1,2,3,4,5,6,7 window size =7
now 1 frame acknowledgement arrive
2,3,4,5,6,7 window = 6
now 1 frame acknowledgement arrive
3,4,5,6,7 window size =5
Ans(A)