The force exerted by a proton on another proton is

Step-by-step solution

A proton has mass, so it exerts a gravitational force on another proton. A proton is a charged particle, so it exerts an electromagnetic force on another proton. A proton is a nucleon, so it exerts a strong nuclear force on another proton. A proton is composed of fermions (quarks), so it also interacts via the weak nuclear force. Therefore, a proton exerts all four fundamental forces on another proton.