Correct Option: B

In one of their most well-known experiments, which took place while Rutherford was a professor at the University of Manchester, the physicists beamed alpha particles at a thin sheet of gold foil. During the experiment, most of the particles passed through the gold foil onto the screen behind it, but some were deflected. Rutherford determined that the particles that made up the gold foil must consist mostly of empty space since most of the alpha particles passed through. However, some regions of the gold must have been too dense to allow the alpha particles through, and this heavy part of the atom was what Rutherford called the nucleus. He concluded that it was the nucleus that held most of the atom's mass.