From the velocity-time graph, given in figure of a particle moving in a straight line, one can conclude that

Displacement in 12s= Area under v−t graph =12×(12+5)4=34mVav= Displacement  Time =3412=176ms−1Hence, (a) is incorrect; (b) is incorrect because during first 3 s, velocity increases from 0 to 4 ms-1 option; (c) is incorrect, because in part AB velocity is constant.