A force between two protons is same as the force between proton and neutron. The nature of the force is

CONCEPT:

• All the forces that we experience every day (and many that we don't even) can be classified into four fundamental forces:

1. Gravity. 
2. The weak force. 
3. Electromagnetism. 
4. The strong force. 

• These 4 forces are known as the four fundamental forces of nature.

1. Gravity: The attraction force between two objects that have mass or energy is called Gravity.
2. The weak nuclear force: The force that is responsible for particle decay is known as the weak nuclear force.
   • This force shows the change of one type of subatomic particle into another 
3. Electromagnetic force: The force that acts between charged particles.
   • Opposite charges attract each other, while the same charges repel each other.
4. The strong nuclear force: This force binds the fundamental particles of matter together to form larger particles.
   • It holds together the quarks that makeup protons and neutrons, and part of the strong force also keeps the protons and neutrons of an atom's nucleus together.
   • This force is the strongest of the four fundamental forces of nature.

EXPLANATION:

• The force between two protons = Force between proton and neutron.
• This force binds proton and neutron together which makes it the strongest force. Though this force acts inside nuclear, this force is known as Strong Nuclear Force.
• So the correct answer is option 2.

• A neutrino that stays close to a neutron can turn the neutron into a proton while the neutrino becomes an electron.
  • This is because of the Weak Nuclear Force.