Answer:
(4) neutrons and protons
Step-by-step explanation:
there exist four fundamental interaction force as following
1). Gravitational force
2) Electromagnetic force
3). Weak Nuclear force
4). Strong Nuclear force
So here we have to find the strong force between the subatomic particles which will have strongest force
So here all interaction between charge particles are always electromagnetic force which is always weaker than nuclear force
So here we can say that the strongest force will be force between neutrons and protons as the force between them is always strong nuclear force due to which they resides into a small space known as nucleus