Answer the following question given this paragraph: 

A proton is a particle in the nucleus of an atom that has a positive electric charge. All protons are identical. It is the number of protons that gives atoms of different elements their unique properties. Atoms of each type of element have a characteristic number of protons. For example, each atom of carbon has six protons, as you can see in Figure below . No two elements have atoms with the same number of protons.


Q: Which particle of an atom has a positive electric charge?

 Choices:

- electron

- nutron

- nucleus

- proton

A:
proton
