Final answer:
In a stable nucleus, the strong nuclear force is stronger than the Coulomb force, allowing the nucleus to remain intact against the repulsive electrostatic forces between protons. Option c.
Step-by-step explanation:
In a stable nucleus, the attractive forces, specifically the strong nuclear force, are stronger than the repulsive forces, such as the Coulomb force between protons. For low-mass nuclei, the strong nuclear force is strong enough to overcome the repulsive electrostatic forces because the nuclear force affects all nucleons within its short-range effectively. However, in larger nuclei, the range of the nuclear force is smaller than the size of the nucleus, which necessitates the addition of more neutrons to keep protons adequately separated and reduce the Coulomb repulsion. If the nucleus becomes too large, though, the Coulomb repulsion from protons can overcome the nuclear attraction, making the nucleus unstable. Option c.