The scattering of a stream of positively charged particles when striking a thin film of gold confirms that

In the gold-foil experiment, most positively charged particles passed through the foil, but a small number were sharply deflected. This showed that an atom’s positive charge and most of its mass are concentrated in a small, dense central region. Therefore, choice A is correct: the positive charge is located in a dense central mass.

AI-written and checked against the verified answer.