Consider a 1-dimensional harmonic oscillator potential (with origin at x=0 ) in the presence of a perturbing potential f(x). Successive energy states are labelled by integers n with the ground state n=0. Which one of the following statements about energy shifts calculated with perturbation theory is incorrect? Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. a If f(x)=f(x) then the first order energy shifts for states with n even vanish b If f(x)=f(x) then the first order energy shifts for states with n odd vanish c If f(x)=f(x) the second order energy shifts for states with n odd vanish. d If f(x)=(x) the energy shifts for states with n odd vanish to all orders. e For f(x)=f(x) the parity of the perturbed states will be the same as the unperturbed ones