Final answer:
The subatomic particles found in the nucleus of an atom are c) protons and neutrons, which are responsible for most of its mass and are known as nucleons.
Step-by-step explanation:
The subatomic particles located in the nucleus of an atom are protons and neutrons. These particles are collectively known as nucleons. Protons have a positive electric charge, while neutrons have no charge and are neutral. The mass number of an atom is the sum of the number of protons and neutrons it contains, which defines the specific type of element, referred to as a nuclide. Atoms are mainly constructed from three fundamental subatomic particles: electrons, protons, and neutrons. While protons and neutrons reside within the nucleus at the centre of the atom, giving it most of its mass, electrons orbit the nucleus in shells and subshells, contributing to an atom's size but not much to its mass. The number of protons in the nucleus determines the identity of the element, with unique atomic numbers assigned to different elements.