Answer :
Answer:
C. the view that the atom cannot be broken down further than protons
Explanation:
Atom is considered as the smallest unit of matter. An atom contains protons and neutrons in the nucleus and electrons orbiting the nucleus in fixed energy shells.
It was thought that atom cannot be broken down further than these particles until quarks were discovered. A proton contains three quarks- 2 up quarks and 1 down quark.