Excerpt from Atomic Theory Clark Benson:
Early twenty-first century technology has given today's scientists the opportunity to
conduct even more complex experiments with atoms. Scientists now use massive
machines called particle accelerators, or "atom smashers." Particle accelerators are capable
of taking subatomic particles, such as an electron, and speeding them up to near the speed
of light. Once the particle has reached the proper speed, it is sent on a collision course
with another particle or atom. The impact breaks up the electron and reveals its inner
parts, giving researchers a glimpse into what makes up the particle. Physicists hope that
continued advances in technology and research will answer one of humankind's most basic
yet important questions: What are we all made of?
Which subject is discussed in paragraph 6?

A)the discovery of neutrons
B)how atoms are put together
C)the person who discovered atoms
D)how subatomic particles are used