Displacement time graph of a particle moving in a straight line is as shown in figure.
From the graph we can conclude that work done on the block is :
.
A. positive from 0 to `t_(1)`
B. negative from `t_(1)` to `t_(2)`
C. zero from `t_(2)` to `t_(3)`
D. negative from `t_(3)` to `t_(4)`
