Final answer:
Atoms, composed of protons, neutrons, and electrons, are the basic units that make up matter, which is defined as anything that occupies space and has mass.
Step-by-step explanation:
Atoms are the foundational components of all matter, with each one consisting of subatomic particles known as protons, neutrons, and electrons. Protons are positively charged, neutrons have no charge, and electrons are negatively charged, balancing the charge of the protons. Atoms bond together to form molecules, which are the substructures that determine the properties of matter.
Substances are made of matter, which in turn, is made up of atoms. While atoms themselves can exist as individual entities, they can also bond with each other to form molecules. Therefore, in answering the student's question regarding what atoms makeup, the most accurate choice would be B: Matter. Matter can be in various states including solids, liquids, and gases, with each state being composed of atoms arranged in different configurations and with varying degrees of interaction between them.