Answer: option B. is much less than that felt by a single proton in a small nucleus.
Explanation:
The strong nuclear force is one of the four forces in nature: 1) strong nuclear force, 2) weak nuclear force, 3) electrostatic force, and 4) gravity.
Strong nuclear force is the strongest of the forces and is resposible for the attraction of the protons and neutrons in the nucleus, and so it is the responsibile for the stability of the atom nuclei.
Neverthelss, it is also a force of very low range it can act only at very small distances. That means that the larger the nucleus the weaker the force.
That is the reason for the unstability of the large atoms.