What Is the Relationship Between an Atom and Matter

What is the relationship between an atom and matter?

A) An atom is the smallest stable unit of matter,and matter is anything that takes up space and has mass.
B) An atom is the largest stable unit of matter,and matter is anything that takes up space and has mass.
C) An atom is a particle with a negative electrical charge,and matter is mass within a gravitational field.
D) An atom is a chemical substance made up of two or more different elements in a fixed proportion,and matter is a pure substance consisting only of atoms with the same atomic number.
E) An atom is the smallest stable unit of matter,and matter is a pure substance consisting only of atoms with the same atomic number.