Particle Classification in the Standard Model

Steps:

• Subatomic particles are broadly classified into hadrons (strong force interactors, quark-based) and leptons (no strong force, like electrons).
• Mesons are composite particles formed by a quark-antiquark pair.
• Baryons are composite particles formed by three quarks (e.g., protons, neutrons).
• Both mesons and baryons belong to the hadron class due to their quark composition.

Why B is correct:

• Hadrons encompass all quark-bound states, including mesons (bosons) and baryons (fermions), per the quark model in particle physics.

Why the others are wrong:

• A: Leptons are fundamental, non-quark particles (e.g., muons, neutrinos) and exclude baryons.
• C: Mesons interact via the strong force and are not leptons.
• D: Neither mesons nor baryons are leptons, as leptons lack quarks.

Final answer: B