A particle free to move along the x-axis has potential energy given by U(x) = k [1-exp -x2] for -∞≤x≤+∞, where k is a positive constant of appropriate dimensions. Then$

• A. The particle is in unstable equilibrium at points away from the origin
• B. There is a force directed away from the origin for any finite nonzero value of x
• C. It has its minimum kinetic energy at the origin if its total mechanical energy is k/2
• D. The motion is simple harmonic for small displacement from x=0