[单选题]
99.15: Given the graph of the velocity v+w, ny3 i8gmiws. time of a du6jz93wh:hh lk;g i+sn ck flying due south for the winter. At what poinz; hk3w9sn +hgj6hi :lt did the duck stop its forward motion?
A. point A
B. point B
C. point C
D. point D
E. None of these
