A block of mass \(m\) is attached to an ideal horizontal spring with spring constant \(k\) and undergoes simple harmonic motion on a frictionless surface. The block's position \(x\) is measured relative to its equilibrium position at \(x = 0\), and it oscillates between the extremes \(x = -A\) and \(x = +A\). Which of the following graphs best represents the elastic potential energy \(U_s\) of the block-spring system as a function of position \(x\)?