Answer:
A. A neutron attracting a proton
Explanation:
Strong nuclear force :
The subatomic particles proton and neutron are held together in the nucleus because of the strong nuclear force. Protons are positively charged and neutrons are neutral particles. We know that like charges repel each other, but still protons and neutrons are held together in the nucleus due to strong nuclear force.
The strong nuclear force is one of the four fundamental forces.
The strong nuclear force is stronger than other three fundamental forces.
The strong nuclear force is effective at very short distance.
The range and relative strength of strong nuclear force is 10⁻¹⁵ m and 10³⁸ with respect to gravitational force respectively.
The strong nuclear force is an attractive force between the protons and neutrons.
Therefore,
A neutron attracting a proton is an example of the strong nuclear force acting in an atom.