Which of the following is an example of a baryon?

a. meson
b. electron
c. lepton
d. proton and neutron

I saw a sight online that said A but on the notes my teacher had us copy it says D.

It is d.

Correct, the answer is option d. The proton and neutron are examples of baryons. Baryons are a class of subatomic particles that are made up of three quarks. The proton is composed of two up quarks and one down quark, while the neutron is composed of one up quark and two down quarks.

To check the accuracy, it is important to refer to reliable sources such as scientific textbooks or trusted educational websites. While online sources can provide valuable information, it is always a good practice to cross-check the information with reputable sources to ensure accuracy. In this case, referring to the notes provided by your teacher could be more reliable than a random website.