What are nucleons?

Explanation:

As the name suggests, nucleons are particles of nucleus.

This means that nucleons are sub-atomic particles that are present within the nucleus of the atom.

We know that protons and neutrons exist inside the nucleus whereas the electrons revolve around the nucleus.

Since electrons exist outside the nucleus, it is not a nucleon.

The positively charged protons and the neutral neutrons are the sub-atomic particles that occupy a small space in the nucleus and are thus called nucleons.

Thus, Nucleons term is used for the collective sum of protons and neutrons present in the nucleus.

Final Answer:

Hence, the correct answer is A: the sum of protons and neutrons present in the nucleus.