Which of the following observations indicates that an atom has neutrons? A.) Some uncharged particles are scattered by a beryllium atom when it hits a gold foil.

B.) Some uncharged particles bounce back from a gold foil when it is bombarded with alpha particles.

C.) A radiation consisting of uncharged particles is emitted when alpha particles strike beryllium atoms.

D.) A radiation which attracts electrons is produced when a beryllium atom is bombarded with alpha particles.