Answer:
(D) atom
Step-by-step explanation:
The atom is the smallest unit of matter that has the properties of a chemical element.
The atom is composed of protons, electrons, and neutrons, they are subatomic particles.
Each chemical element has an atom that identifies it, but all atoms are composed of subatomic particles, this means that all atoms have electrons, neutrons, and protons.
Depending on the number of subatomic particles that we have is what gives the properties to each atom.
A set of two or more atoms, of one or more elements, form a molecule