When alpha particles are directed onto atoms in a thin metal foil, some make very close collisions with the nuclei of the atoms and are scattered at large angles. If an alpha particles with an initial kinetic energy of 5 MeV happens to be scattered through an angle of 180, which of the following must have been its distance of the closest approach to the scattering nucleus? (Assume that the metal foil is made of silver, with Z = 50.) 50/3 fm A. 1.22 x B. 2.9 x 10-4 m C. 1.0 x 10-12 m D. 3.0 x 10-8, E. 1.7 x 107 m m