What are the two particles that make up the nucleus of an atom?

The nucleus of an atom is composed of two types of particles: protons and neutrons. Protons are positively charged particles that define the atomic number and determine the identity of an element, while neutrons are neutral particles that contribute to the mass of the atom and help stabilize the nucleus. This combination of protons and neutrons allows for the existence of the variety of elements we observe in nature.

Other combinations provided in the choices do not accurately represent the particles found in the nucleus. Electrons, for instance, are negatively charged particles that orbit the nucleus and are not part of it. Quarks are fundamental constituents of protons and neutrons, but they are not typically referred to when discussing the composition of the nucleus in this context. Thus, protons and neutrons are correctly identified as the particles that make up the nucleus.