Understand where subatomic particles are located in an atom and what their characteristics are.

There's the electrons that surround the nucleus in shells. Electrons have a negative charge and way almost nothing.
 

In the nucleus, theres protons and neutrons. Neutrons have no charge while protons have a positve charge.

All atom have no charge unless they are ions where theres either more electrons than protons or vice versa.
Negative ions are attracted to positive ions e vice versa

Sorry i think the answer is b