A theoretical particle that bonds quarks together as well as protons and neutrons is called a _______.

• A. Gluon
• B. Photon
• C. Electron
• D. Neutrino

Answer: (A)

The mediator of the strong force in quantum chromodynamics is what binds quarks together inside protons, neutrons, and other hadrons. Quarks carry color charge, and they interact by exchanging gluons, which themselves carry color. This exchange acts like a binding glue, pulling quarks together and keeping these particles bound. Gluons can interact with each other as well, which helps explain why the strong force behaves the way it does—getting stronger as quarks try to separate and leading to confinement.

The other options don’t serve this role. A photon carries electromagnetic force and binds charged particles in many contexts, but it doesn’t bind quarks by the color force. Electrons and neutrinos are fermions, not force carriers, so they don’t mediate the binding inside hadrons.