Answer: Option B.
Strong nuclear force Gravity.
Explanation:
Nuclear force is the strongest force while Gravity is the weakest force. Strong nuclear force is the strongest force because it's act and hold atoms of matter together. It also binds neutrons and protons together to form atomic nuclei and it's has strength of 1.
Gravity is considered the weak force out of the four fundamental forces because it has a very small strength of 10^40 than electromagnetic force.
