Why are experiments often performed in laboratories?
O A. They are better at representing the real world.
O B. There are fewer variables to control.
C. Scientists only want to know what happens in labs.
O D. It is harder to control variables in a laboratory.

Which of these statements is true? a. quarks pair with leptons to form protons and neutrons. b. quarks pair with bosons to form photons. c. quarks pair with photons to form protons and neutrons. d. quarks pair with other quarks to form protons and neutrons. e. quarks pair with electrons to form protons.