31. The velocities of drivers A and B are shown as functions of time in the figure below. Driver B
starts her car at the instant driver A passes her. At which moment on the graph are drivers A and
B side by side?
(A) 0 s, 2 s
(B) 0 s, 4 s
(C) 2 s, 4 s
(D) 2 s, 6 s
(E) 4 s, 6 s