Which set of labels should be used to correctly complete the atomic model below?
a.
1 - Electron
2 - Nucleus
3 - Neutron
4 - Proton
b.
1 - Proton
2 - Electron
3 - Neutron
4 - Nucleus
c.
1 - Neutron
2 - Proton
3 - Nucleus
4 - Electron
d.
1 - Proton
2 - Neutron
3 - Electron
4 - Nucleus
