An electron passes through a region with a step-like potential shown in the figure for x<0. The potential is V(x)=V_(0) for x>=0. The electron moves left to right, and its total energy is twice. What is the potential for x>=0? A) V(x)=V_(0) B) V(x)=V_(0)/2 C) V(x)=2V_(0) D) V(x)=2V_(0)/2