What two particles make up the nucleus of an atom?

The nucleus of an atom is composed of protons and neutrons, which are both types of nucleons. Protons are positively charged particles that determine the atomic number of an element, while neutrons are neutral particles that contribute to the mass of the atom and help to stabilize the nucleus by offsetting the repulsive forces between the positively charged protons.

These two particles are fundamental to the structure of an atom, as they reside at its center and define its characteristics. This arrangement creates a stable nucleus essential for the existence of matter as we know it. Other particles listed in the options, such as electrons, are found in orbitals surrounding the nucleus but do not contribute to its composition directly. Thus, the correct pairing of particles that constitute the nucleus is protons and neutrons.