For a particle moving along the x-axis, x-t graph is as given in figure. Mark the correct statement(s).

Velocity is given by the slope of the x-t graph. Here the slope is zero at A and at peak of region CD and bottom most point of EF . For AB and EF, acceleration is positive. For these regions, graph is concave up.For BC and DE, acceleration is zero as here velocity is constant. For CD, acceleration is negative as graph is concave down for this region.