Which of the following is an example of a baryon? a. meson c. lepton b. electron d. proton

A meson because Each baryon has a corresponding antiparticle known as an anti baryon in which quarks are replaced by their corresponding anti quarks. For example, a proton is made of two up quarks and one down quark, while its corresponding antiparticle, the anti proton, is made of two up anti quarks and one down antiquary.