[单选题]
10.11: Consider the wdb2 :8,pel 93ralbxrmotis05v.:;j1ut co ;frirz (kkgm on of an object given by the velocity vs. time graph shown. For which time(s) is the acc:z;ji k0 cutg( os15 mkfr.r;veleration of the object equal to 0?
A. Only at t=2.0s
B. Only at t=5.0s
C. Only at t=8.0s
D. At t=2.0s and 5.0s
E. At t=2.0s, 5.0s and 8.0s