Answer the following question given this paragraph: 

30.2 Discovery of the Parts of the Atom: Electrons and Nuclei • Atoms are composed of negatively charged electrons, first proved to exist in cathode-ray-tube experiments, and a positively charged nucleus. • All electrons are identical and have a charge-to-mass ratio of.


Q: Atoms are composed of negatively charged electrons and a positively charged what?

 Choices:

- DNA segment

- neutron

- bond

- nucleus

A:
nucleus
