Answer:
B) mostly empty space and has a small, positively charged nucleus
Step-by-step explanation:
In the gold foil experiment, positively-charged alpha particles were directed towards a gold foil sheet. During the experiment, most of the particles went through the gold foil. However, a select few alpha particles were met with resistance and bounced off the sheet.
This proves that the gold atoms, which made up the gold foil sheet, were mostly empty space as most of the alpha particles passed through it. Furthermore, the particles which bounced off the sheet must have hit small, positively-charged nuclei. The nuclei must have been positive because similar charges repel each other. In other words, if the nuclei were negatively-charged, the positively-charged alpha particles would not bounce off the sheet, but instead "stick" to it.