Answer:
A. Because protons are positively charged and like charges repel
Explanation:
In the nucleus of an atom are subatomic particles as follows: proton and neutron. Protons are positively charged subatomic particles while neutrons are neutrally charged. Following the principle that "like charges repel one another", protons in the nucleus of an atom tend to repel one another.
Hence, the need for neutrons to form a strong force with the self-repelling protons. This bonding between the neutrons and protons help keep the nucleus together. Therefore, protons wouldn’t be able to handle being packed into the nucleus without neutrons because protons are positively charged and like charges repel.