The skateboarder will have the greatest potential energy at point G.
Potential energy is the energy possessed by a body by virtue of its position. The gravitational potential energy of a body is given by the expression,
Here, m is the mass of the body, g the acceleration due to gravity and h is the height of the body from the ground.Thus as h increases, the potential energy increases.
From the figure, it can be seen that the highest point in the skateboarder's trajectory is G. hence, he would have the highest potential energy at the point G.