Final answer:
The particle among the given options that is classified as a baryon is the proton (C). Electrons and neutrinos are leptons, quarks make up baryons but are not themselves baryons, and photons are bosons.
Step-by-step explanation:
The question asks us to identify which of the following particles are baryons: electrons, neutrinos, protons, quarks, and photons. Baryons are a family of subatomic particles that are made up of three quarks and include protons and neutrons. Therefore, the correct answer is C) protons, as they are composed of three quarks and are part of the baryon family.
Electrons and neutrinos are examples of leptons, another type of fundamental particle that does not fall into the baryon category. Quarks are the fundamental constituents that make up particles like protons and neutrons, but they themselves are not baryons. Photons are quanta of light and are considered bosons, not baryons.
In conclusion, the proton is the particle among the given options that is classified as a baryon.