The graph between kinetic energy $E_K$ and velocity $V$ is

Velocity-time graph of a particle of mays $2 \mathrm{kg}$ moving in a straight line is as shown in figure. Work done by all the forces on the particle is 

As shown in the diagram, a particle is to be carried from point $A\text{ to} C$ via paths $\left(\mathrm{I}\right), \left(\mathrm{II}\right)\text{ and} \left(\mathrm{III}\right)$ in gravitational field, then which of the following statements is correct.