Classifying particles in the Standard Model

Steps:

• Identify fundamental particles as elementary leptons and quarks, not composed of smaller parts.
• Recognize electrons and neutrinos as leptons, a class of fundamental fermions.
• Distinguish hadrons as composite particles formed by quarks via the strong force.
• Classify protons and neutrons as baryons, made of three quarks each.

Why A is correct:

• In the Standard Model, electrons and neutrinos are elementary leptons, defined as fundamental particles without internal structure.

Why the others are wrong:

• B: Hadrons are composite particles bound by the strong force, unlike leptons.
• C: Leptons do not experience the strong nuclear force; protons and neutrons are baryons that do.
• D: Quarks are fundamental building blocks; protons and neutrons are composite particles of three quarks.

Final answer: A